[{"meta":{"title":"ASCII Table","short":"Mapping of characters as a series of binary digits to integers","topic":"encoding ascii"},"html":"

DEC	HEX	BIN	CHAR		DEC	HEX	BIN	CHAR		DEC	HEX	BIN	CHAR		DEC	HEX	BIN	CHAR
0	00	`0000 0000`	NUL (null)		32	20	`0010 0000`	`(space)`		64	40	`0100 0000`	`@`		96	60	`0110 0000`	`
1	01	`0000 0001`	SOH (start of header)	33	21	`0010 0001`	`!`	65	41	`0100 0001`	`A`	97	61	`0110 0001`	`a`
2	02	`0000 0010`	STX (start of text)	34	22	`0010 0010`	`"`	66	42	`0100 0010`	`B`	98	62	`0110 0010`	`b`
3	03	`0000 0011`	ETX (end of text)	35	23	`0010 0011`	`#`	67	43	`0100 0011`	`C`	99	63	`0110 0011`	`c`
4	04	`0000 0100`	EOT (end of transmission)	36	24	`0010 0100`	`$`	68	44	`0100 0100`	`D`	100	64	`0110 0100`	`d`
5	05	`0000 0101`	ENQ (enquiry)	37	25	`0010 0101`	`%`	69	45	`0100 0101`	`E`	101	65	`0110 0101`	`e`
6	06	`0000 0110`	ACK (acknowledge)	38	26	`0010 0110`	`&`	70	46	`0100 0110`	`F`	102	66	`0110 0110`	`f`
7	07	`0000 0111`	EL (bell)	39	27	`0010 0111`	`'`	71	47	`0100 0111`	`G`	103	67	`0110 0111`	`g`
8	08	`0000 1000`	BS (backspace)	40	28	`0010 1000`	`(`	72	48	`0100 1000`	`H`	104	68	`0110 1000`	`h`
9	09	`0000 1001`	HT (horizontal tab)	41	29	`0010 1001`	`)`	73	49	`0100 1001`	`I`	105	69	`0110 1001`	`i`
10	0A	`0000 1010`	LF (line feed - new line)	42	2A	`0010 1010`	`*`	74	4A	`0100 1010`	`J`	106	6A	`0110 1010`	`j`
11	0B	`0000 1011`	VT (vertical tab)	43	2B	`0010 1011`	`+`	75	4B	`0100 1011`	`K`	107	6B	`0110 1011`	`k`
12	0C	`0000 1100`	FF (form feed - new page)	44	2C	`0010 1100`	`,`	76	4C	`0100 1100`	`L`	108	6C	`0110 1100`	`l`
13	0D	`0000 1101`	CR (carriage return)	45	2D	`0010 1101`	`-`	77	4D	`0100 1101`	`M`	109	6D	`0110 1101`	`m`
14	0E	`0000 1110`	SO (shift out)	46	2E	`0010 1110`	`.`	78	4E	`0100 1110`	`N`	110	6E	`0110 1110`	`n`
15	0F	`0000 1111`	SI (shift in)	47	2F	`0010 1111`	`/`	79	4F	`0100 1111`	`O`	111	6F	`0110 1111`	`o`
16	10	`0001 0000`	DLE (data link escape)	48	30	`0011 0000`	`0`	80	50	`0101 0000`	`P`	112	70	`0111 0000`	`p`
17	11	`0001 0001`	DC1 (device control 1)	49	31	`0011 0001`	`1`	81	51	`0101 0001`	`Q`	113	71	`0111 0001`	`q`
18	12	`0001 0010`	DC2 (device control 2)	50	32	`0011 0010`	`2`	82	52	`0101 0010`	`R`	114	72	`0111 0010`	`r`
19	13	`0001 0011`	DC3 (device control 3)	51	33	`0011 0011`	`3`	83	53	`0101 0011`	`S`	115	73	`0111 0011`	`s`
20	14	`0001 0100`	DC4 (device control 4)	52	34	`0011 0100`	`4`	84	54	`0101 0100`	`T`	116	74	`0111 0100`	`t`
21	15	`0001 0101`	NAK (negative acknowledge)	53	35	`0011 0101`	`5`	85	55	`0101 0101`	`U`	117	75	`0111 0101`	`u`
22	16	`0001 0110`	SYN (synchronous idle)	54	36	`0011 0110`	`6`	86	56	`0101 0110`	`V`	118	76	`0111 0110`	`v`
23	17	`0001 0111`	ETB (EOF transmitionblock)	55	37	`0011 0111`	`7`	87	57	`0101 0111`	`W`	119	77	`0111 0111`	`w`
24	18	`0001 1000`	CAN (cancel)	56	38	`0011 1000`	`8`	88	58	`0101 1000`	`X`	120	78	`0111 1000`	`x`
25	19	`0001 1001`	EM (end of medium)	57	39	`0011 1001`	`9`	89	59	`0101 1001`	`Y`	121	79	`0111 1001`	`y`
26	1A	`0001 1010`	SUB (substitute)	58	3A	`0011 1010`	`:`	90	5A	`0101 1010`	`Z`	122	7A	`0111 1010`	`z`
27	1B	`0001 1011`	ESC (escape)	59	3B	`0011 1011`	`;`	91	5B	`0101 1011`	`[`	123	7B	`0111 1011`	`&lbracket;`
28	1C	`0001 1100`	FS (file separator)	60	3C	`0011 1100`	`<`	92	5C	`0101 1100`	`\\`	124	7C	`0111 1100`	`\|`
29	1D	`0001 1101`	GS (group separator)	61	3D	`0011 1101`	`=`	93	5D	`0101 1101`	`]`	125	7D	`0111 1101`	`&rbracket;`
30	1E	`0001 1110`	RS (record separator)	62	3E	`0011 1110`	`>`	94	5E	`0101 1110`	`^`	126	7E	`0111 1110`	`~`
31	1F	`0001 1111`	US (unit separator)	63	3F	`0011 1111`	`?`	95	5F	`0101 1111`	`_`	127	7F	`0111 1111`	DEL (delete)

informations from https://fr.cppreference.com/w/cpp/language/ascii

","path":"sheets/computer-ascii","file":"sheets/computer/ascii"},{"meta":{"title":"Languages Theory and Automatas","short":"Study of formal languages and automata as abstract models of computation used to design and analyze algorithms","topic":"automatas"},"html":"

linkIntroduction

For introduction, See [Propositional Calculus and Logic](/sheets/maths/discrete/#propositional-calculus-and-logic)

linkAlphabet

Every finished set

$Binairy: A = \\lbrace 0,1 \\rbrace$
$Latin: A = \\lbrace a,b,\\dots,z,A,B,\\dots,Z \\rbrace$
$ASCII: A = \\lbrace a,b,\\dots,z,A,B,\\dots,Z\\,0,1,\\dots,9 \\rbrace$

","path":"sheets/computer-automatas","file":"sheets/computer/automatas"},{"meta":{"title":"Docker container manager","short":"How to deploy and manage containerized applications","topic":"virtualization docker"},"html":"

linkFast Help

Instruction	Command
Pull image	`docker pull hello-world`
List of containers images	`docker images -a`
Create container	`docker create --name container_name ubuntu`
Run container	`docker run hello-world`
Get container id	`sudo docker ps -aqf "name=container_name"`
Run a saved image	`code>docker run -it -p 8091:8091 container_name`
Operational bash cmd	`docker exec -ti 2769d51daeb2 bash`
Commit container	`docker commit 2769d51daeb2`
Stop container	`docker stop 2769d51daeb2`
Remove container	`docker rm 2769d51daeb2`
Remove image	`docker rmi 2769d51daeb2`
List of running container	`docker ps`
Clean and remove all containers	`docker system prune`
Rename image	`docker tag 18455f1ec44d "container_name"`
Create VM	`docker-machine create \\--driver virtualbox --virtualbox-disk-size "40000" default`
Delete VM	`docker rm default`
Docker login	`docker login -u "myusername" -p "mypassword" docker.io`
Docker ID	`docker tag 18455f1ec44d myusername/ubuntu_container_name:latest`
Docker push	`docker push docker.io/mlhoutel/ubuntu_container_name:latest`

linkDocker Setup

OS	Installation Link
Linux	`sudo apt-get install docker-ce docker-ce-cli containerd.io`
Mac	https://hub.docker.com/editions/community/docker-ce-desktop-mac/
Windows Pro	https://hub.docker.com/editions/community/docker-ce-desktop-windows/
Windows Family	https://github.com/docker/toolbox/releases

https://www.docker.com/ - https://hub.docker.com/

linkConnect to the VM

user: docker\npwd: tcuser

Get the VM ip with

ifconfig eth1

Set the azert keyboard

su docker\ntce-load -wi kmaps\nsudo loadkmap < /usr/share/kmap/azerty/fr-latin9.kmap

Use Putty

SessionWindowSelectionAction = Compromise\npaste : ctrl + shift + V

Use SSH

ssh docker@ip_machine

Install nginx server

install nginx server: docker run -d -p 8080:80 nginx\nopen webpage: http://ip_machine:8080/

Edit nginx webpage:

cd /usr/share/nginx/html

Get Nano:

apt-get update\napt-get install apt-file\napt-file update\napt-get install nano

","path":"sheets/computer-docker","file":"sheets/computer/docker"},{"meta":{"title":"Fluent apis","short":"Design pattern used in software development to create an interface for configuring an object in a clear and concise way, often using a chain of method calls to build up a complex configuration.","topic":"design fluent-api java"},"html":"

linkApi use

Main

package windows;\n\npublic final class Main {\n\n\tpublic static void main(String[] args) {\n\n\t\tFrameBuilder frameBuilder = new FrameBuilder(\"A\");\n\n\t\tFrame frame = frameBuilder\n\t\t\t.title(\"Frame A\")\n\t\t\t.size(200, 100)\n\t\t\t.section(\"content\")\n\t\t\t\t.section(\"header\")\n\t\t\t\t\t.label(\"Hello\")\n\t\t\t\t\t.end()\n\t\t\t\t.end()\n\t\t\t.section(\"body\")\n\t\t\t\t.button(\"World!\")\n\t\t\t\t.end()\n\t\t\t.collect();\n\n\t\tString generated = frame.execute();\n\n\t\tSystem.out.println(\"Output generated code:\");\n\t\tSystem.out.println(generated);\n\t}\n}

linkBuilders

Frame builder

package windows;\n\nimport java.util.ArrayList;\n\npublic class FrameBuilder {\n\n\tpublic String name = \"\";\n\tpublic ArrayList<SectionBuilder<FrameBuilder>> sections = new ArrayList<SectionBuilder<FrameBuilder>>();\n\n\tpublic String title = \"\";\n\tpublic int width = 0;\n\tpublic int height = 0;\n\n\tpublic FrameBuilder(String name) {\n\t\tthis.name = name;\n\t}\n\n\tpublic FrameBuilder title(String title) {\n\t\tthis.title = title;\n\t\treturn this;\n\t}\n\n\tpublic FrameBuilder size(int width, int height) {\n\t\tthis.width = width;\n\t\tthis.height = height;\n\n\t\treturn this;\n\t}\n\n\tpublic SectionBuilder<FrameBuilder> section(String label) {\n\t\tSectionBuilder<FrameBuilder> sectionBuilder = new SectionBuilder<FrameBuilder>(label, this);\n\n\t\tthis.sections.add(sectionBuilder);\n\n\t\treturn sectionBuilder;\n\t}\n\n\tpublic Frame collect() {\n\t\tFrame f = new Frame(this.name, this.title, this.width, this.height);\n\n\t\tfor (SectionBuilder<FrameBuilder> s : this.sections) {\n\t\t\tf.addSection(s.collect(this.name));\n\t\t}\n\n\t\treturn f;\n\t}\n\n}

Section builder

package windows;\n\nimport java.util.ArrayList;\n\n/**\n * @param <T> Pile of types\n *  - FrameBuilder for root\n *  - SectionBuilder<...> for sub levels\n *\n *  T = parent object\n *  SectionBuilder<T> = current type\n *  SectionBuilder<SectionBuilder<T>> = sub sections type\n */\npublic class SectionBuilder<T> {\n\n\tpublic String name = \"\";\n\tpublic T parent = null;\n\tpublic ArrayList<SectionBuilder<SectionBuilder<T>>> sections = new ArrayList<SectionBuilder<SectionBuilder<T>>>();\n\n\tpublic String label;\n\tpublic String button;\n\n\tpublic SectionBuilder(String name, T parent) {\n\t\tthis.name = name;\n\t\tthis.parent = parent;\n\t}\n\n\tpublic SectionBuilder<T> label(String label) {\n\t\tthis.label = label;\n\t\treturn this;\n\t}\n\n\tpublic SectionBuilder<T> button(String button) {\n\t\tthis.button = button;\n\t\treturn this;\n\t}\n\n\tpublic SectionBuilder<SectionBuilder<T>> section(String label) {\n\t\tSectionBuilder<SectionBuilder<T>> sectionBuilder = new SectionBuilder<SectionBuilder<T>>(label, this);\n\n\t\tthis.sections.add(sectionBuilder);\n\n\t\treturn sectionBuilder;\n\t}\n\n\tpublic T end() {\n\t\treturn this.parent;\n\t}\n\n\tpublic Section collect(String parentName) {\n\t\tSection f = new Section(this.label, this.button, parentName);\n\n\t\tfor (SectionBuilder<SectionBuilder<T>> s : this.sections) {\n\t\t\tf.addSection(s.collect(parentName));\n\t\t}\n\n\t\treturn f;\n\t}\n}

linkGenerators objects

Frame

package windows;\n\nimport java.util.ArrayList;\n\npublic class Frame {\n\tpublic String name = \"\";\n\tpublic String title = \"\";\n\tpublic int width = 0;\n\tpublic int height = 0;\n\n\tpublic ArrayList<Section> sections = new ArrayList<Section>();\n\n\tpublic Frame(String name, String title, int width, int height) {\n\t\tthis.name = name;\n\t\tthis.title = title;\n\t\tthis.width = width;\n\t\tthis.height = height;\n\t}\n\n\tpublic void addSection(Section s) {\n\t\tthis.sections.add(s);\n\t}\n\n\tpublic String execute() {\n\t\tString program = \"import javax.swing.JFrame;\r\n\"\n\t\t\t\t+ \"import javax.swing.JLabel;\r\n\"\n\t\t\t\t+ \"import javax.swing.JButton;\r\n\"\n\t\t\t\t+ \"import javax.swing.SwingUtilities;\r\n\"\n\t\t\t\t+ \"import java.awt.FlowLayout;\r\n\"\n\t\t\t\t+ \"public class FrameApplication {\r\n\"\n\t\t\t\t+ \"public static void main(String[] args) {\r\n\"\n\t\t\t\t+ \"SwingUtilities.invokeLater(new Runnable() {\r\n\"\n\t\t\t\t+ \"public void run() {\r\n\";\n\n\t\tprogram += \"JFrame \" + this.name + \" = new JFrame()\r\n\";\n\t\tprogram += this.name + \".setLayout(new FlowLayout());\r\n\";\n\t\tprogram += this.name + \".setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);\r\n\";\n\t\tprogram += this.name + \".setTitle(\" + this.title + \");\r\n\";\n\t\tprogram += this.name + \".setSize(\" + this.width + \", \" + this.height + \");\r\n\";\n\n\t\tfor (Section s : this.sections) {\n\t\t\tprogram += s.execute();\n\t\t}\n\n\t\tprogram += this.name + \".setVisible(true);\r\n\"\n\t\t\t\t+ \"}\r\n\"\n\t\t\t\t+ \"});\r\n\"\n\t\t\t\t+ \"}\r\n\"\n\t\t\t\t+ \"}\";\n\n\t\treturn program;\n\n\t}\n}

Section

package windows;\n\nimport java.util.ArrayList;\n\npublic class Section {\n\tpublic static int sectionId = -1;\n\n\tpublic String id;\n\tpublic String label;\n\tpublic String button;\n\tpublic String parentName;\n\n\tpublic ArrayList<Section> sections = new ArrayList<Section>();\n\n\tpublic Section(String label, String button, String parentName) {\n\t\tthis.id = Integer.toString(sectionId++);\n\t\tthis.parentName = parentName;\n\t\tthis.label = label;\n\t\tthis.button = button;\n\t}\n\n\tpublic void addSection(Section s) {\n\t\tthis.sections.add(s);\n\t}\n\n\tpublic String execute() {\n\t\tString program = \"\";\n\n\t\tif (this.label != null) {\n\t\t\tString labelName = \"label\" + this.parentName + this.id;\n\n\t\t\tprogram += \"JLabel \" + labelName + \" = new JLabel();\r\n\"\n\t\t\t + this.parentName + \".add(\" + labelName + \");\r\n\"\n\t\t\t+ labelName + \".setText(\"\" + this.label + \"\");\r\n\";\n\t\t}\n\n\t\tif (this.button != null) {\n\t\t\tString buttonName = \"button\" + this.parentName + this.id;\n\n\t\t\tprogram += \"JButton \" + buttonName + \" = new JButton();\r\n\"\n\t\t\t + this.parentName + \".add(\" + buttonName + \");\r\n\"\n\t\t\t+ buttonName + \".setText(\"\" + this.button + \"\");\r\n\";\n\t\t}\n\n\t\tfor (Section s : this.sections) {\n\t\t\tprogram += s.execute();\n\t\t}\n\n\t\treturn program;\n\t}\n}

","path":"sheets/computer-fluent","file":"sheets/computer/fluent"},{"meta":{"title":"Structures and Paradigms","short":"Ways of organizing and storing data and approaches to writing and structuring code","topic":"data paradigms"},"html":"

linkModularity and Typing

linkIntroduction

Evolution of the Languages towards an increasingly modular and abstract programming

Assembly => C => C++ => Java => Js => Ts

linkCreating a new Type

Creating a new Type (TypeScript) : example of the Car

Two points of view when defining a new type:

Internal: How to build and manage the elements (how to build a car?)
External: How to use the instances of that element (how to drive a car?)

   \t// Defining an impementation of a type différents Layers:\n   class Car {\n   \t/* Attributes (values, fields, properties) */\n   \tprivate number price\n   \tprivate string brand\n   \tprivate string plate\n\n   \t\t/* Methods (Factories, Constructors, Accessors, Functions) */\n\n   \t\t/* Factories (Builders) */\n   \tconstructor() // Multiple implementations with the overload\n   \tconstructor(price: number, brand: string, plate: string) {\n   \t\tthis.price = price\n   \t\tthis.brand = brand\n   \t\tthis.plate = plate\n   \t}\n   \t// Garbage collection (ex: c++ ~destructor)\n\n   \t\t/* Constructors (Setters) */\n   \tsetPrice(price : number) { this.price = price }\n   \tsetBrand(brand : string) { this.brand = brand }\n   \tsetPlate(plate : string) { this.plate = plate }\n\n   \t\t/* Accessors (Getters) */\n   \tgetPrice() : number { return this.price }\n   \tgetBrand() : string { return this.brand }\n   \tgetPlate() : string { return this.plate }\n\n   \t\t/* Functions */\n   \tcomputeSomething(): number { return 0 }\n   }

linkData Persistence

Immutability: Keep the initial state, each computation create a new object

Benefits: Permit to avoid errors due to the change of the object. For instance, if multiple entities can access the object at the same time, or if you just don\\‘t want the state of the object to change.
DrawBack: Can be heavier on memory due to the initialisation of a new element for each change in the object state

class ImmutableNumber {\n\tconstructor(private value: number) {}\n\n\tgetValue(): number {\n\t\treturn this.value;\n\t}\n\n\tplusNumber(other: ImmutableNumber): ImmutableNumber {\n\t\treturn new ImmutableNumber(this.getValue() + other.getValue());\n\t}\n\n\tminusNumber(other: ImmutableNumber): ImmutableNumber {\n\t\treturn new ImmutableNumber(this.getValue() - other.getValue());\n\t}\n}

Mutability: The state of the object can change, allows to edit it

Benefits: Some case just need to have an object evolution.
DrawBack: Harder to manage the states, and riskier.

class MutableNumber {\n\tconstructor(private value: number) {}\n\n\tgetValue(): number {\n\t\treturn this.value;\n\t}\n\tsetValue(value: number) {\n\t\tthis.value = value;\n\t}\n\n\tplusNumber(other: MutableNumber) {\n\t\tthis.setValue(this.getValue() + other.getValue());\n\t}\n\n\tminusNumber(other: MutableNumber) {\n\t\tthis.setValue(this.getValue() - other.getValue());\n\t}\n}

linkHierarchy: Aggregation and Inheritance

Aggregation (Has a X)

Code factorisation with the aggregation of the differents classes

Multiples forms:

Shared Aggregation (objects are independants)
Symbiosis (same life duration)

Example:

class Driver {\n\t/* Driver class implementation */\n}\n\nclass Wheel {\n\t/* Wheel class implementation */\n}\n\nclass Frame {\n\t/* Frame class implementation */\n}\n\n/*\n   \tThe Car class is an example of the Aggregation:\n   \tIt HAS a driver, wheels and a frame\n   */\n\nclass Car {\n\tprivate driver: Driver;\n\tprivate wheels: Array<Wheel>;\n\tprivate frame: Frame;\n\n\tconstructor(driver: Driver) {\n\t\tthis.driver = driver;\n\t\tthis.wheels = [new Wheel(), new Wheel(), new Wheel(), new Wheel()];\n\t\tthis.frame = new Frame();\n\t}\n\n\t/*\n   \t\tWith this exemples, we could also say thet these components\n   \t\tdon't have the same relation with the Car class:\n\n   \t\t- The Wheels and the Frame seems pretty linked to the Car\n   \t\t  In fact, we can see that they are only created in the Car constructor.\n   \t\t  => We could say that the Car is in symbiosis with the Wheels and the Frame\n   \t\t  ... but it's not realy true, the wheels could be changed, the car\n   \t\t  would still be the same. The interpretation is realy specific to what you need\n\n   \t\t- The Driver seems completely independant from the rest of the pieces. It is\n   \t\tpassed by parameter in the constructor, and we can emit the supposition that\n   \t\tthe driver can be changed, for instance if he sells the car to another Driver\n   \t\t=> We could say that the Driver is in a shared aggregation with the Car\n   \t*/\n}

Inheritance (Is a X)

Polymorphism : Multiplicity of essences

Data storage:

Covariant (accept object that are more specialized)
Contravariant (don\\‘t accept any more specialized object)

Example:

class Vehicle {\n\tprivate driver: Driver;\n\tprivate wheels: Array<Wheel>;\n\tprivate frame: Frame;\n\n\t/* Vehicle implementation */\n}\n\n/* A Car IS a Vehicle, it will have the same attributes and methods... */\nclass Car extends Vehicle {\n\t/* Car class implementation */\n}\n\n/* ... but moreover, it can implement new attributes and methods! */\nclass Truck extends Vehicle {\n\tprivate trailer: Trailer; // The trailer is specific to the truck\n\n\t/* Truck class implementation */\n}\n\n/*\n   \tWe can see that the Polymorphism allows to store multiple childs\n   \tof the Car class in the same Array, that's really usefull\n   */\nlet MyVehicles: Array<Vehicles> = [new Car(), new Truck()];

linkLayered architectures

Universal architecture:

Low Layer (internal): accessors and builders
High Layer (external): services implemented using the low layer

Factorisation Cases:

Simple Inheritance: descending aproach (factoring the bottom layer)
Simple Inheritance: ascending aproach (factoring the top layer)
Multiple Inheritance: independant bottom and top layers
Agregation with Delegation: composition of the top layer (inject dependances)

","path":"sheets/computer-paradigms","file":"sheets/computer/paradigms"},{"meta":{"title":"Vim & VS Code shortcuts","short":"Set of keyboard shortcuts to help users efficiently navigate and edit text","topic":"shortcuts vs-code vim cmder"},"html":"

linkVS Code

Cheat Sheet Config

Switch Tab	`Ctrl`\n\t+\n\t`[n]`
Quit Tab	`Ctrl`\n\t+\n\t`F4`
Commands	`Ctrl`\n\t+\n\t`Shift`\n\t+\n\t`P`
Navigate in open files	`Ctrl`\n\t+\n\t`Tab`
New Terminal	`Ctrl`\n\t+\n\t`Shift`\n\t+\n\t`ù`

linkFile Utils

VSCode Extension

linkVim

VSCode Extension

Cheat Sheet

:set encoding=utf-8

linkModes

┌──────────────┐     [Ctrl+C] >     ┌──────────────┐        [:] >       ┌───────────────┐\n│  --Insert--  │   <════════════>   │  --Normal--  │   <════════════>   │  --Command--  │\n└──────────────┘      < [i]         └──────────────┘     < [Ctrl+C]     └───────────────┘\n                                            ∧\n                                            ║    ∧\n                                      [v]   ║ [Ctrl+C]\n                                       ∨    ║\n\t\t\t\t\t    ∨\n                                    ┌──────────────┐\n                                    │  --Visual--  │\n                                    └──────────────┘

link–Normal–

Navigation

Navigation [n] lines	`[n]`\n\t+\n\t`i j k l`
Navigation [n] words	`[n]`\n\t+\n\t`w b / W B`
Move start/end of line	`0 / $`
Goto line [n]	`[n]`\n\t+\n\t`gg`
Search char in line	`f[char] / F[char]`
Navigate in search	`Enter`\n\tthen\n\t`; / ,`
Search text in file	`/[text] / ?[text]`
Navigate in search	`Enter`\n\tthen\n\t`n / N`
Find and replace	`:%s/find/replace/g`
Move half page up/down	`Ctrl`\n\t+\n\t`D / U`
Center screen on cursor	`zz`

V (visual)\nat (go closing bracket)\no / O (go back and forth)

Selection

Selection	`v`
Copy/Cut selection	`y / d`
Paste before/after cursor	`P / p`

Macros

Record macro [name]	`q[name]`
Stop recording	`q`
Play macro [name]	`@[name]`

linkChrome

Cheat Sheet

Search	`Ctrl`\n\t\t+\n\t`F`
Open selected link	`Ctrl`\n\t\t+\n\t`Enter`
New tab	`Ctrl`\n\t\t+\n\t`t`
Navigate to tab	`Ctrl`\n\t\t+\n\t`[n]`
Close tab	`Ctrl`\n\t\t+\n\t`F4`
Reopen closed tab	`Ctrl`\n\t\t+\n\t`Shift`\n\t\t+\n\t`t`
Precedent / Next	`Alt`\n\t\t+\n\t`[arrows]`
Search bar	`Ctrl`\n\t\t+\n\t`l`

linkCmder

Config Cheat Sheet

New tab	`Ctrl`\n\t\t+\n\t`t`
Close tab	`Ctrl`\n\t\t+\n\t`w`
Swap to tab [n]	`Ctrl`\n\t\t+\n\t`[n]`
New Powershell tab	`Shift`\n\t\t+\n\t`Alt`\n\t\t+\n\t`2`
Copy current tab right/bottom	`Ctrl`\n\t\t+\n\t`Shift`\n\t\t+\n\t`R/B`
Move to tab	`Ctrl`\n\t+\n`Shift`\n\t+\n`[arrows]`

","path":"sheets/computer-shortcuts","file":"sheets/computer/shortcuts"},{"meta":{"title":"Sphinx documentation generator","short":"Convert source code documentation written in the reStructuredText format into a variety of output formats, such as HTML and PDF","topic":"docs sphinx python"},"html":"

linkIntroduction

linkSetup

linkInstallation with Anaconda

Install Anaconda:

https://docs.anaconda.com/anaconda/install/windows/

   $ conda create -n sphinx python=3.7 # Create the env we will use for sphinx\n   $ conda activate sphinx \t\t\t# Activate the env (reopen a new command if error)\n   (sphinx) $ conda install sphinx \t# Install Sphinx from the package repository\n\n   # Extentions (themes, converter, highligting etc)\n   (sphinx) $ conda install -c anaconda recommonmark \t\t# If you want to use the .md language in addition to the .rst base one\n   (sphinx) $ conda install -c anaconda sphinx_rtd_theme \t# Read The Doc theme is a cool theme to begin, see example at https://sphinx-rtd-theme.readthedocs.io/en/stable/\n   (sphinx) $ conda install -c conda-forge nbsphinx\t\t# If you want to have embedded notebooks into the documentation\n   (sphinx) $ conda install -c conda-forge sphinx-copybutton # Add a copy button on the code blocks\n\n   (sphinx) $ mkdir website_folder\t\t# Create the website folder\n   (sphinx) $ cd website_folder\t\t# Go into the folder\n   (sphinx) $ sphinx-quickstart\t\t# Initialize the website\n\n   (sphinx) $ make html\n   (sphinx) $ start chrome _build/html/index.html

linkWebsite Setup

linkSource Folder

source                                          *Root*\n├─── _static                                    *Ressource*\n│     ├─── main.js\n│     ├─── style.css\n│     ├─── image.png\n│     ├─── favicon.ico\n│     └─── logo.svg\n├─── _templates                                 *Templates*\n│     └─── layout.html\n├─── pages                                      *Pages*\n├─── conf.py                                    *Config*\n└─── index.rst                                  *Main Page*

linkConf File

   # Configuration file for the Sphinx documentation builder.\n\n   /* ... */\n\n   # -- Project information -----------------------------------------------------\n\n   project = 'Project-Name'\n   copyright = 'Copyright text'\n   author = 'Author Name'\n   release = '1.0.0'\n\n   /* ... */\n\n   # -- General configuration ---------------------------------------------------\n\n   extensions = ['recommonmark','sphinx_rtd_theme','nbsphinx','sphinx_copybutton']\n   templates_path = ['_templates']\n   exclude_patterns = []\n   html_theme = 'sphinx_rtd_theme'\n   pygments_style = 'monokai'\n\n   html_static_path = ['_static']\n   html_css_files = ['style.css']\n   html_js_files = ['main.js']\n\n   html_title = "Website Title"\n   html_short_title = "Title"\n   html_logo = "_static/logo.svg"\n   html_favicon = "_static/favicon.ico"\n\n   html_show_sourcelink = False\n   html_theme_options = {\n       'logo_only': True,\n       'prev_next_buttons_location': 'both'\n   }

linkCheat Sheets

linkReStructuredText (.rst)

   ============================\n   Main Title\n   ============================\n\n   Sub Title\n   ============================\n\n   Sub Sub Title\n   ----------------------------\n\n   Sub Sub Sub Title\n   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n\n   :Title note:\n\n   .. contents:: Table of Contents\n   \t:local:\n\n   \t.. toctree::\n   \t:maxdepth: 2\n   \t:caption: Maths Tree\n\n   ``inline code``\n\n   Code example::\n\n   \tif (a == b) { /* code */ }\n\n   .. code-block::\n\n   \tif (a == b) { /* code */ }\n\n   .. code-block:: c\n   \t:linenos:\n   \t:lines: 1, 3-5\n       :start-after: 3\n       :end-before: 5\n\n   \tif (a == b) { /* code */ }\n\n   .. literalinclude:: file.c\n   \t:language: c\n   \t:linenos:\n\n   +---------------------+---------+---+\n   | 1                   | 2       | 3 |\n   +---------------------+---------+---+\n\n   +---------+---------+-----------+\n   | 1       | 2       | 3         |\n   +=========+=========+===========+\n   | 4                 | 5         |\n   +---------+---------+-----------+\n   | 6       | 7       | 10        |\n   +---------+---------+           |\n   | 8       | 9       |           |\n   +---------+---------+-----------+\n\n   .. csv-table:: a title\n      :header: "1", "2", "3"\n      :widths: 20, 20, 20\n\n      "4", "5", "6"\n      "7", "8", "9"\n\n   .. image:: image.jpg\n       :width: 200px\n       :align: center\n       :height: 100px\n       :alt: alternate text\n\n   .. figure:: image.jpg\n       :width: 200px\n       :align: center\n       :height: 100px\n       :alt: alternate text\n       :figclass: align-center\n\n       Caption text\n\n   \t.. todo::\n   .. seealso:: Note\n   .. note:: Note\n   .. warning:: Note\n   .. Attention:: Lorem ipsum dolor sit amet, consectetur adipiscing elit.\n   .. Caution:: Lorem ipsum dolor sit amet, consectetur adipiscing elit.\n   .. DANGER:: Lorem ipsum dolor sit amet, consectetur adipiscing elit.\n   .. WARNING:: Lorem ipsum dolor sit amet, consectetur adipiscing elit.\n   .. Error:: Lorem ipsum dolor sit amet, consectetur adipiscing elit.\n   .. Hint:: Lorem ipsum dolor sit amet, consectetur adipiscing elit.\n   .. Important:: Lorem ipsum dolor sit amet, consectetur adipiscing elit.\n   .. Note:: Lorem ipsum dolor sit amet, consectetur adipiscing elit.\n   .. Tip:: Lorem ipsum dolor sit amet, consectetur adipiscing elit.\n\n   \t.. admonition:: Custom Title\n\n   \t    Lorem ipsum dolor sit amet, consectetur adipiscing elit.\n\n   \t.. topic:: Title\n\n   \t\tLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.\n   \tUt enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.\n   \tuis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.\n   \tExcepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.\n\n   \t.. sidebar:: Sidebar Title\n   \t:short: Sidebar short\n\n   \t\tLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.\n   \tUt enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.\n   \tuis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.\n   \tExcepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.\n\n   \t:download:`download samplet.py <sample.py>`\n   :math:`alpha > \beta`\n   .. math::\n\n   \tn_{mathrm{offset}} = sum_{k=0}^{N-1} s_k n_k

linkMarkdown

sphinx-quickstart\n\npip install pypandoc\n\nimport pypandoc output = pypandoc.convert_file('file.md', 'rst')\n\nwith open("file.rst", "w", encoding="utf-8") as f:\n   f.write(output)

","path":"sheets/computer-sphinx","file":"sheets/computer/sphinx"},{"meta":{"title":"Unix OS family","short":"group of computer operating systems that share a common heritage and many of the same design principles, and are known for their stability, flexibility, and portability","topic":"unix commands"},"html":"

linkFast Help

Instruction	Command
Move to	`cd directory_name`
Current folder	`pwd`
Binary location	`which command_name`
List folders	`ls [-l (detail)][-a (hidden)][-F (type)][-h (size)][-t (date)][-r (reverse)]`
Disk usage	`du [-h (size)][-a (all)][-s (sum)]`
Display all files	`cat file_name [-n (lines)]`
Display page files	`less file_name [SPACE (scroll)][ENTER (next)][B (back)][Q (quit)][/text_to_find (find) + n(next)/N(back)]`
Display part file	`head file_name/tail file_name [-n 10 (lines)][-f (follow)]`
Create file	`touch file_name [second_file_name...]`
Create directory	`mkdir folder_name [-p (path folders)]`
Copy file	`cp file_name copy_name [*.jpg (wildcard)][-R (recursive)]`
Move file	`mv file_name folder_name [*.jpg (wildcard)]`
Rename file	`mv file_name new_file_name`
Remove file	`rm file_name [second_file_name...][-i (ask)][-f (force)][-v (verbose)][-r (recursive)]`
Link file	`ln file_name target_name`

linkLinux directory

/                                               *Root directory*\n├───bin                                         *Users programs*\n├───boot                                        *System booting*\n├───dev                                         *Devices (ex:CD)*\n├───etc                                         *Config folder*\n├───home                                        *Users folders*\n│     ├───userA\n│     └───userB\n├───lib                                         *Shared libraries*\n├───media                                       *Medias (ex:USB)*\n├───mnt                                         *Temporary medias*\n├───opt                                         *Programs add-ons*\n├───proc                                        *System infos*\n├───root                                        *Root user folder*\n├───sbin                                        *System programs*\n├───tmp                                         *Temporary folder*\n├───usr                                         *Users programs*\n└───var                                         *Datas and Logs*

","path":"sheets/computer-unix","file":"sheets/computer/unix"},{"meta":{"title":"C++","short":"General-purpose programming language, developed as an extension of the C programming language.","topic":"language c++"},"html":"

linkIntroduction

linkHistory of the C language

C is an imperative procedural language. It was designed to be\ncompiled to provide low-level access to memory.

It was developed between 1972 and 1973 by Dennis Ritchie, initially to\nconstruct utilities running on the Unix operating system. During the\n1980s, C gradually gained popularity and became one of the most widely\nused programming languages.

Today, the C is not as popular as it used to be, but it’s still a very\ngood language to begin with and understand the rules of programmation.\nMoreover, it is realy fast and light and permit to manage the low\nlevel datas with the pointers, one thing that most of the high level\nlanguages can’t.

linkEvolution toward C++

C++ was developped in 1979 by Bjarne Stroustrup. It was firstly named\nC with Classes by it’s creator, then renamed in 1983. It is an\nevolution toward an more Object Oriented programming language, that it\nimplements with Classes, Inheritance and many others functionnalities.

The current version of it is C++17 (2017). A new one is standardized\nby the ISO every 3 years since 2011, the next versions is C++20,\nalready released but not every functionnality are supported yet on the\ncompilators.

linkProgramming in C

linkFirst Program : helloworld.c

#include <stdio.h>\n\nint main() {\n   printf(\"Hello, World!\");\n   return 0;\n}

This file is a simple .txt file, I just edited the extension. Like\nyou can see, it is .c for the base language, and .cpp for C++, but\nthese are not the only ones that exist, there are many others, like .h\nand .hpp for the header files, .cuh and .cu for CUDA...

To have your program working, you’ll have to build the file: To put\nit simply, we get the source code (helloworld.c) and put it into a\ncompiler with the right settings and dependancies, and this compiler\noutput and executable (helloworld.exe) that you can run from your\nmachine. We will use the command line to build and run this file,\nit’s realy easy.

linkCompiling

But first of all, you will need a compiler. That’s a piece of software\nthat transform your file from readable instructions (in english) into\na language that your machine can understand: binaries (0 and 1),\nthat’s what an .exe file is (if you open it with and text editor, you\nwill see some stranges charaters).

Many C compiler exists, (See all)

I recommand these ones:

GCC (from GNU, Open sources): Download GCC from GNU
MSVC (from Microsoft Visual Studio): Download Visual Studio

For this example, I’m using GCC 10.0.1, the base command line from Windows 10 and the text editor Sublime Text 3

I recommand to install GCC from MinGW instead of compiling it yourself.

you will find explanations on how to proceed here

linkSetup GCC and compiling a basic program

If you are on windows, you can press Windows + Q then type cmd to open the command line.
1. Open it and try to type gcc and press Enter
2. If you have a message that look like that: 'gcc' is not recognised as an internal command, make sure that you downloaded GCC and go to the next step: We will add GCC to the environment variables so the system can find it.
3. The system need to know where the compiler is to understand that you call it from the command line.
  1. Press Windows + Q then type env and open Edit the system environment variables
  2. Click on the Environment variables button
  3. Select Path and click on Edit
  4. Finally, click on New and paste the link to GCC (ex: C:\\MinGW\\bin)
4. Open a new command and type gcc, now it should work and diplay that message: gcc: fatal error: no input files. compilation terminated.
Now we will compile the file helloworld.c
1. Open a command in the same directory as the C file
2. type gcc helloworld.c -o helloworld.exe
3. then ./helloworld.exe
4. The program will output this string: Hello, World!
Great, you have now a working basis to begin your learning of the C and C++ languages.

linkCompilator settings and flags

You can call the compiler by gcc for the C compiler and g++\nfor the C++ compiler. I explain here the flags that I use and find\nthe most important, but you can find all the gcc flags\nHERE. If you\nwant, you can even create a .bat file to automate the command and\nlaunch the compilations.

Command Syntax:

gcc [options] [source files] [object files] -o output file

If you don’t put -o output file, the output file will be a.exe per default.

Add libraries:

-I %libpath%\\include -L %libpath%\\lib -l libfileA -l libfileB

-I define the include folder, generally where the headers files .h are
-L define the folder where to look at the source files
-l define the name/link for the library to include .dll if the lib is dynamically compiled, and .lib if it is staticaly compiled

Warnings and Errors:

The Errors Flags begin with a -W (for Warning):

-w disable all warnings messages, the program will keep compiling
-Wall enables all the warnings for minors errors
-Wextra enables some extra warning flags that -Wall don’t\nactivate
-Werror make all warnings into errors.
-Wfatal-errors abort compilation on the first error

Debug Flags:

-Wall -Wextra -Wold-style-cast -Woverloaded-virtual -Wfloat-equal -Wwrite-strings -Wpointer-arith -Wcast-qual -Wcast-align -Wconversion -Wshadow -Weffc++ -Wredundant-decls -Wdouble-promotion -Winit-self -Wswitch-default -Wswitch-enum -Wundef -Wlogical-op -Winline

For the Debug config, you can put all the flags to detect and display every error or unrecommanded feature of your code.

Release Flags

-Werror -Wfatal-errors

For the Release config, the process abort at the first error

The Debug Flags begin with a -g (for Generate debug informations)

-g0 no debug informations
-g1 minimal debug informations
-g default debug informations
-g3 maximal debug informations

I recommand to stay with the default value -g and switch to higher level -g3 if you have no clue on the error.

Optimisation:

The Optimisation Flags begin with a -O (for Optimisation)

Option	Optimization Level	Execution Time	Code Size	Memory Usage	Compilation Time
`-O0`	compilation time	+	+	-	-
`-O1 /-O`	code size/exe time	-	-	+	+
`-O2`	code size/exe time	- -	=	+	+ +
`-O3`	code size/exe time	- - -	=	+	+ + +
`-Os`	code size	=	-	=	++
`-Ofast`	imprecise fast math	- - -	=	+	+ + +

informations from https://www.rapidtables.com/code/linux/gcc/gcc-o.html#optimization

linkImport and use Libraries

linkIncludes and Dependancies

To include a library we use the #include command.

#include <library.h> when the headers folder is already linked in\nthe compiler
#include "folder/library.h" to search in a specific folder with\nthe path

List of the most common and used system libraries:

C Input/Output library: #include <stdio.h>
C General library: #include <stdlib.h>
C Numerics library : #include <cmath.h>
C Strings library: #include <string.h>
C Time library: #include <time.h>
C++ Time library: #include <chrono>
C++ Treads library: #include <thread>

informations from https://en.cppreference.com/w/cpp/header

linkNamespace and utilities

When you use multiple libraries, it could be some conflicts under\nnames between some libraries, that’s why we use namespaces.

“Namespaces provide a method for preventing name conflicts in large projects.”\nsource

We can use namespaces like that: sf::...

sf::RectangleShape rectangle(sf::Vector2f(120,50));

Or like that: namespace sf { ... }

namespace sf {\n  RectangleShape rectangle(Vector2f(120,50));\n}

Or even like that: using namespace sf;

using namespace sf;\n\nRectangleShape rectangle(Vector2f(120,50));

I recommand the first two methods, the problem with the last one is\nthat you loose all the purpose of the namespace, and it’s confusing\nwhen you want to use both functions from libraries that would be in\nconflict, you will have to mix the third and the first method...

linkCheat Sheets

linkUsefull Informations

Unofficial Documentation: https://en.cppreference.com/w/

About Cpp

Type of Language: Procedural, Object-Oriented
Born in: 1985
Caracteristics: Statically typed, low level, fast
Popularity: 5.8% (6th) src
Usefull for: softwares, games, embedded…

linkBasic C Cheat Sheet

linkTypes and Variables

/s/ stand for Signed and /u/ for Unsigned

NUMERICS

Name	Syntax	Size	Min	Max	Letter	Aliases
Short `/s/` Integer	`short int`	`16+ bits`	-32 768 (−2¹⁵)	32 767 (2¹⁵−1)	`%h`	`short` `signed short`
Short `/u/` Integer	`unsigned short int`	`16+ bits`	0 (0)	65 535 (2¹⁶−1)	`%h`	`unsigned` `short`
Integer `/s/`	`int`	`16+ bits`	-32 768 (−2¹⁵)	32 767 (2¹⁵−1)	`%i`	`signed` `signed int`
Integer `/u/`	`unsigned int`	`16+ bits`	0 (0)	65 535 (2¹⁶−1)	`%i`	`unsigned` `unsigned int`
Long `/s/` Integer	`long int`	`32+ bits`	-2 147 483 648 (−2³¹)	2 147 483 647 (2³¹−1)	`%l`	`signed long int`
Long `/u/` Integer	`unsigned long int`	`32+ bits`	0 (0)	4 294 967 295 (2³²−1)	`%l`	`unsigned long`
Long Long `/s/` Integer	`long long int`	`64+ bits`	-9.223e-15 (−2⁶³)	9.223e+15 (2⁶³−1)	`%ll`	`signed long long`
Long Long `/u/` Integer	`unsigned long long int`	`64+ bits`	0 (0)	18.446e+15 (2⁶⁴−1)	`%ll`	`unsigned long long`

Integers are not rounded they are truncated toward 0. I recommand to not use short appart if you know what you do.

CHARS

Name	Syntax	Size	Min	Max	Letter	Aliases
Char `/s/`	`char`	`8+ bits`	-128 (−2⁷)	127 (2⁷−1)	`%hh`	`signed char`
Char `/u/`	`unsigned char`	`8+ bits`	0 (0)	255 (2⁸−1)	`%hh`
char8_t `/u/`	`unsigned char`	`8+ bits`	0 (0)	255 (2⁸−1)	`%hh`
char16_t `/u/`	`unsigned char`	`8+ bits`	0 (0)	255 (2⁸−1)	`%hh`
char32_t `/u/`	`unsigned char`	`8+ bits`	0 (0)	255 (2⁸−1)	`%hh`
wchar_t `/u/`	`unsigned char`	`8+ bits`	0 (0)	255 (2⁸−1)	`%hh`

Chars are just integers linked to an characted by the ascii table.

informations from https://fr.cppreference.com/w/cpp/language/ascii

linkInput Output

#include <stdio.h>\n\nint main() {\n\n\t// We define the age variable as an Integer\n\tint age;\n\n\t// We use printf to output a line of text from a string\n\tprintf(\"Enter an integer for your age: \");\n\n\t// Scanf convert the input variable and put it in age by reference.\n\t// It will not stop until scanf detect a non null \"string\" input.\n\tscanf(\"%i\", &age);\n\n\t// Then we use printf to output the string with the variable.\n\tprintf(\"You are %i years old.\nGreat!\", age);\n\n\t// fflush clean the output buffer, it discards any buffered data that has been fetched from\n\t// the underlying output file, but has not been consumed by the application. Thanks to that\n\t// we are sure to have a clean output the next time we call the function printf.\n\tfflush(stdin);\n}

output

Enter an integer for your age: 19\nYou are 19 years old.\nGreat!

Note:

If you input a you will have an output of 4194432. That’s because\nscanf don’t convert the string to an int. When the value is not in\nthe right format, it will get the memory location.

For the boundaries, an input of 2147483647 will output 2147483647,\nbut if you try to enter a value of 2147483648 you will have an\noutput of -2147483648. Thats because the signed value is greater\nthan $2^31-1$. The default int boundaries are 32bits on my\nx64 processor

linkVariables, Tests and Loops

VARIABLES DECLARATIONS

int main() {\n\n\t// Variable declaration and Operators\n\tint value = 10;\n\n\tvalue += 5; // 10+5 = 15\n\tvalue -= 3; // 15-3 = 12\n\tvalue *= 2; // 12*2 = 24\n\tvalue /= 4; // 24/4 = 6\n\n\tvalue++; // 6+1 = 7\n\t++value; // 7+1 = 8\n\n\tvalue--; // 8-1 = 7\n\t--value; // 7-1 = 6\n\n\t// Binary Operators\n\tint binA = 60, binB = 6;\n\n\tbinA & binB // 60 AND 6 = 4\n\t// 0011 1100 (60)\n\t// 0000 0110 (6)\n\t// ---------------\n\t// 0000 0100 (4)\n\n\tbinA | binB // 60 OR 6 = 62\n\t// 0011 1100 (60)\n\t// 0000 0110 (6)\n\t// ---------------\n\t// 0011 1110 (62)\n\n\tbinA ^ binB // 60 XOR 6 = 58\n\t// 0011 1100 (60)\n\t// 0000 0110 (6)\n\t// ---------------\n\t// 0011 1010 (58)\n\n\t~binB // NOT 6 = -9\n\t// (0) 0110 (6)\n\t// ---------------\n\t// (1) 1001 (-9)\n\n\tbinB <<= 3 // 6 LEFT-SHIFTED BY 3 = 48\n\t// 0000 0110 (6)\n\t// ---------------\n\t// 0011 0000 (48)\n\n\tbinA = binA >> 2 // 60 RIGHT-SHIFTED BY 2 = 15\n\t// 0011 1100 (60)\n\t// ---------------\n\t// 0000 1111 (15)\n\n\t// Tests\n\tbool A = true; // A=true=1\n\tbool B = !A; // B=false=0\n\n\tif (A) { /* (IS) TRUE */ }\n\tif (!A) { /* (IS NOT) FALSE */ }\n\n\tif (A && B) { /* (AND) FALSE */ }\n\tif (A || B) { /* (OR) TRUE */ }\n\tif(!A != !B) { /* (XOR) TRUE */ }\n\n\tif (A==1) { /* (EQUAL) TRUE */ }\n\tif (A!=42) { /* (NOT EQUAL) TRUE */ }\n\tif (A>1) { /* (GREATER THAN) FALSE */ }\n\tif (A>=1) { /* (GREATER OR EQUAL) TRUE*/ }\n\tif (A<-2) { /* (LOWER THAN) FALSE*/ }\n\tif (A<=B) { /* (LOWER OR EQUAL) FALSE*/ }\n}

TESTS

if (Condition) {\n}\n\nif(Condition)\n  // Action\n\nif (Condition) {\n  // Action\n} else if (Condition) {\n  // Action\n} else {\n  // Action\n}\n

SWITCH

switch (variable) {\n  case 1: // Action\n    break;\n  case 2: // Action\n    break;\n  default: // Action\n}

LOOPS

\ndo {\n  // Action\n} while(conditions);\n\nwhile (conditions) {\n  // Action\n}\n\nfor (int i = 0; i < 10; ++i) {\n  // Action\n}

You can use break; to stop a loop.

linkRandom numbers

RANDOM

#include <stdio.h> \t// NULL\n#include <stdlib.h> //srand, rand\n#include <time.h> \t// time\n#include <math.h>\t// pow\n\nint main() {\n\n\trand()%100; // Rand integer from 0 to 99\n\n\tsrand(time(NULL)); // Initialise the random generator with the internal clock as a Seed\n\trand()%100; // This one is a more random number (current seed is quite special)\n\n\tsrand (1); // The random generator's seed is 1 by default, go put it back to see\n\trand()%100; // This next random number should be the SAME as the first one\n\n\t// To have a delimited random number, you can use this:\n\tint max=112, min=75;\n\tsrand(time(NULL));\n\tfor (int i = 0; i < 10; ++i)\n\t{\n\t\tint random = (rand()%(max-min))+min;\n\t\tprintf(\"%i \", random); // (ex: 110 109 98 89 105 94 79 103 93 101)\n\t}\n}

You can see the max of rand() with RAND_MAX (32767+). For betters randoms number you can use the BOOST library.

linkArrays

ARRAYS

#include <stdio.h>\n\nint main()\n{\n\t// We declare an array of 4 integers\n\tint numbers[5] = {0, 1, 2, 4, 8};\n\n\t// You can also declare arrays like that, the array will have the size of the elements you define\n\tfloat prime[] = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97};\n\n\t// You can compute it's size like that\n\tint length = sizeof(numbers) / sizeof(int); // 20 / 4 = 5\n\n\tfor (int i=0; i<length; i++) {\n\t\tprintf(\"%i \", numbers[i]); //display: 0 1 2 4 8\n\t}\n\n\tnumbers[0] = 20; // {20, 1, 2, 4, 8}\n\tnumbers[3] = 10; // {20, 1, 2, 10, 8}\n\n\t// But the solution with the size calculation is not optimal: it can be a problem when\n\t// the array is not declared on the stack but on the heat, a better solution can be :\n\n\tconst int better_length = 10;\n\tint better_numbers[better_length];\n\n\tfor(int i=0; i<better_length; i++) {\n\t\tbetter_numbers[i] = i;\n\t}\n}

STRINGS

#include <string.h>\n\nint main()\n{\n\t// The end delimiter of an array of chars is always '\u0000'\n\tchar word[6] = {'G','u','i','t','a','r'};\n\n\t// We can define multi-dimentionnal arrays like that\n\tchar week[7][9];\n\n\tstrcpy(week[0], \"Lundi\");\n\tstrcpy(week[1], \"Mardi\");\n\tstrcpy(week[2], \"Mercredi\");\n\tstrcpy(week[3], \"Jeudi\");\n\tstrcpy(week[4], \"Vendredi\");\n\tstrcpy(week[5], \"Samedi\");\n\tstrcpy(week[6], \"Dimanche\");\n\n\tstrlen(word); // The length of word is 6\n\n\tswitch(strcmp(week[0], week[1])) {\n\n\t\tcase 0: // week[0] == week[1]\n\t\t\tbreak;\n\t\tcase -1: // week[0] < week[1]\n\t\t\tbreak;\n\t\tcase 1: // week[0] > week[1]\n\t\t\tbreak;\n\t}\n}\n

string entry;\nint test;\n\ndo {\n  // Test if the input string is composed of chars bewteen 'a' and 'z'\n  test = scanf(\"%1[a-z]c\", &entry);\n} while(test != 1)

linkFunctions

int random(int min, int max) {\n  return (rand()%(max-min)) + min;\n}\n\nvoid nothing() {\n   // return nothing ...\n}

linkStructures

RECTANGLE STRUCTURE EXAMPLE

#include <stdio.h>\n\n// We define the Rectangle structure.\ntypedef struct {\n\n\t// It contains some of it's Properties like the position (x,y) and the size (height, width)\n\tfloat x;\n\tfloat y;\n\tfloat height;\n\tfloat width;\n\n\t// Structs are not like Classes, wecannot create functions inside it.\n\n} Rectangle;\n\n// We create a function to calculate the area of a Rectangle\nfloat calcArea(Rectangle r) {\n\treturn r.height * r.width;\n}\n\n// We alse create a function to print the properties of the struct, it call the precedent function to compute the area\nvoid toString(Rectangle r) {\n\tprintf(\"structure: Rectangle\n + Position: [%f, %f]\n + Size: [%f, %f]\n + Area: %f\", r.x, r.y, r.height, r.width, calcArea(r));\n}\n\nint main() {\n\n\t// We instantiate a Rectangle with the name rectangle\n\tRectangle rectangle;\n\n\t// We edit it's properties\n\trectangle.x = 10.0;\n\trectangle.y = 2.0;\n\trectangle.height = 3.7;\n\trectangle.width = 6.5;\n\n\t// We call the toString function to see if the properties have changed\n\ttoString(rectangle);\n}

output

   \tstructure: Rectangle\n    + Position: [10.000000, 2.000000]\n    + Size: [3.700000, 6.500000]\n    + Area: 24.050000

Take care of the order in which you declare your structure fields, because it will impact the size of the final data.

For instance…

#include <iostream>\n#include <stdint.h>\n\n// small first\nstruct large\n{\n  uint8_t a;\n  uint32_t b;\n  uint8_t c;\n  uint32_t d;\n};\n\n// small last\nstruct small\n{\n  uint32_t a;\n  uint32_t b;\n  uint8_t c;\n  uint8_t d;\n};\n\n// packed\nstruct __attribute__((packed)) packed\n{\n  uint32_t a;\n  uint32_t b;\n  uint8_t c;\n  uint8_t d;\n};\n\nint main()\n{\n  uint8_t sz_plain = 2 * sizeof(uint8_t) + 2 * sizeof(uint32_t);\n  uint8_t sz_large = sizeof(large);\n  uint8_t sz_small = sizeof(small);\n  uint8_t sz_packed = sizeof(packed);\n\n  std::cout << \"plain  = \" << std::to_string(sz_plain) << std::endl;\n  std::cout << \"large  = \" << std::to_string(sz_large) << std::endl;\n  std::cout << \"small  = \" << std::to_string(sz_small) << std::endl;\n  std::cout << \"packed = \" << std::to_string(sz_packed) << std::endl;\n\n  // plain  = 10\n  // large  = 16\n  // small  = 12\n  // packed = 10\n}

linkPointers and Smart pointers

TODO

linkBasic C++ Cheat Sheet

linkMacros

#include <stdio.h>\n\n#define NUMARGS(...)  (sizeof((int[]) { __VA_ARGS__ }) / sizeof(int))\n#define FIRSTARG(...) FIRSTARG0(__VA_ARGS__, ERROR_NO_ARGS_PROVIDED) // assign an undeclared var to trigger the compiler error\n#define FIRSTARG0(X, ...) X // to avoid \"warning: ISO C99 requires rest arguments to be used [enabled by default]\" when 1 arg\n\nint main() {\n        printf(\"%i\n\", NUMARGS(1,2,3,4));\n        printf(\"%i\n\", FIRSTARG(1));\n        printf(\"%i\n\", FIRSTARG(1,2,3));\n        return 1;\n}

linkArrays

#include <iostream>\n#include <array>\n#include <vector>\n\n// We are not editing the values so we add const\nvoid Function(const std::vector<int>& values) {\n\t// ...\n}\n\nint main()\n{\n\t// We initialize an array of 5 int\n\tstd::array<int, 5> numbers;\n\n\tfor (int i=0; i<numbers.size();i++) {\n\t\tnumbers[i] = i*10;\n\t\tstd::cout << numbers[i] << std::endl;\n\t}\n\n\n\t// TODO Vector type and arrays of pointers, redifine\n\tstd::vector<int> values;\n\tvalues.push_back(10);\n\n\tfor (int i=0; i<values.size(); i++) {\n\t\tstd::cout << values[i] << std::endl;\n\t}\n\n\t// Or even\n\n\tfor (const values& v : int) {\n\t\tstd::cout << v << std::endl;\n\t}\n\n\tvalues.erase(values.begin() + 2); // Erase the third element, we cannot just pas the position\n\tvalues.clear(); // Set back size to 0\n\n\t// We pass the values by Reference to avoid copies\n\tFunction(values);\n\n\t// HEAT vs STACK, copying and optimisation...\n\treturn 0;\n}

linkStack & Heap

constexpr double pow(double x, long long n) noexcept {\n    if (n > 0) [[likely]]\n        return x * pow(x, n - 1);\n    else [[unlikely]]\n        return 1;\n}

c style

struct MyStruct { };\n\n// on heap\nMyStruct* s = malloc(sizeof(struct MyStruct));\n\n// on stack\nMyStruct s = {};

c++ style

class MyClass { };\n\n// on heap\nMyClass* c = new MyClass();\n\n// on stack\nMyClass c = MyClass();

linkBy reference vs By copy

// by copy\nint getIndex(MyClass a) {\n    return a.index;\n}\n\n// by ref (+ const)\nint getIndex(const &MyClass a) {\n    return a.index;\n}

linkInheritances

#include <iostream>\n#include <string>\n#include <vector>\n#include <memory>\n#include <chrono>\n\ntemplate <typename T>\nusing spt = std::shared_ptr<T>;\n\ntemplate <typename T>\nusing vec = std::vector<T>;\n\nclass Base\n{\nprotected:\n    int value = 0;\n\npublic:\n    virtual void print() = 0;\n    virtual void perf() = 0;\n};\n\nclass A : public Base\n{\npublic:\n    void print()\n    {\n        std::cout << \" - A derived class\" << std::endl;\n    }\n    void perf() { value++; }\n    void specA() { value++; }\n};\n\nclass B : public Base\n{\npublic:\n    void print()\n    {\n        std::cout << \" - B derived class\" << std::endl;\n    }\n    void perf() { value++; }\n    void specB() { value++; }\n};\n\nclass Container\n{\nprivate:\n    int value = 0;\n\npublic:\n    Container(spt<Base> d) : data(d) {}\n    void perf() { value++; }\n    spt<Base> data;\n};\n\nvoid call()\n{\n    vec<spt<Base>> vec = {};\n\n    A tmp_A = A();\n    B tmp_B = B();\n\n    std::cout << \"\nTest objects print\" << std::endl;\n    tmp_A.print();\n    tmp_B.print();\n\n    std::cout << \"\nTest pointer print\" << std::endl;\n    Base *ptr_A = &tmp_A;\n    Base *ptr_B = &tmp_B;\n    ptr_A->print();\n    ptr_B->print();\n\n    std::cout << \"\nTest smart print\" << std::endl;\n    spt<Base> sptr_A = std::make_shared<A>(tmp_A);\n    spt<Base> sptr_B = std::make_shared<B>(tmp_B);\n\n    sptr_A->print();\n    sptr_B->print();\n\n    std::cout << \"\nTest array print\" << std::endl;\n    vec.push_back(sptr_A);\n    vec.push_back(sptr_B);\n\n    for (auto ptr : vec)\n    {\n        ptr->print();\n\n        if (A *uncast_A = dynamic_cast<A *>(ptr.get()))\n        {\n            uncast_A->specA();\n        }\n        else if (B *uncast_B = dynamic_cast<B *>(ptr.get()))\n        {\n            uncast_B->specB();\n        }\n    }\n}\n\nvoid perf()\n{\n    vec<A> vec_A = {};\n    vec<B> vec_B = {};\n\n    vec<spt<A>> vec_sptA = {};\n    vec<spt<B>> vec_sptB = {};\n\n    vec<spt<Base>> vec_sptBase = {};\n    vec<Container> vec_container = {};\n\n    for (int i = 0; i < 10000000; ++i)\n    {\n        vec_A.push_back(A());\n        vec_B.push_back(B());\n\n        vec_sptA.push_back(std::make_shared<A>(A()));\n        vec_sptB.push_back(std::make_shared<B>(B()));\n\n        vec_sptBase.push_back(std::make_shared<A>(A()));\n        vec_sptBase.push_back(std::make_shared<B>(B()));\n\n        vec_container.push_back(Container(std::make_shared<A>(A())));\n        vec_container.push_back(Container(std::make_shared<B>(B())));\n    }\n\n    std::cout << \"\nVectors size\" << std::endl;\n    std::cout << \" - vecA + vec_B: \t\t\" << std::to_string(vec_A.size() + vec_B.size()) << std::endl;\n    std::cout << \" - vec_sptA + vec_sptB:  \t\" << std::to_string(vec_sptA.size() + vec_sptB.size()) << std::endl;\n    std::cout << \" - vec_sptBase:  \t\t\" << std::to_string(vec_sptBase.size()) << std::endl;\n    std::cout << \" - vec_container:  \t\t\" << std::to_string(vec_container.size()) << std::endl;\n\n    std::cout << \"\nDurations\" << std::endl;\n    {\n        auto start = std::chrono::steady_clock::now();\n\n        for (auto obj : vec_A)\n        {\n            obj.perf();\n        }\n\n        for (auto obj : vec_B)\n        {\n            obj.perf();\n        }\n\n        auto end = std::chrono::steady_clock::now();\n\n        auto diff = std::chrono::duration_cast<std::chrono::microseconds>(end - start).count();\n        std::cout << \" - simple array of obj iteration: \t\t\" << std::to_string(diff) << \"μs\" << std::endl;\n    }\n\n    {\n        auto start = std::chrono::steady_clock::now();\n\n        for (auto ptr : vec_sptA)\n        {\n            ptr->perf();\n        }\n\n        for (auto ptr : vec_sptB)\n        {\n            ptr->perf();\n        }\n\n        auto end = std::chrono::steady_clock::now();\n\n        auto diff = std::chrono::duration_cast<std::chrono::microseconds>(end - start).count();\n        std::cout << \" - array of shared_ptr iteration: \t\t\" << std::to_string(diff) << \"μs\" << std::endl;\n    }\n\n    {\n        auto start = std::chrono::steady_clock::now();\n\n        for (auto ptr : vec_sptBase)\n        {\n            ptr->perf();\n        }\n\n        auto end = std::chrono::steady_clock::now();\n\n        auto diff = std::chrono::duration_cast<std::chrono::microseconds>(end - start).count();\n        std::cout << \" - merged array of shared_ptr iteration: \t\" << std::to_string(diff) << \"μs\" << std::endl;\n    }\n\n    {\n        auto start = std::chrono::steady_clock::now();\n\n        for (auto ptr : vec_sptBase)\n        {\n            if (A *uncast_A = dynamic_cast<A *>(ptr.get()))\n            {\n                uncast_A->specA();\n            }\n            else if (B *uncast_B = dynamic_cast<B *>(ptr.get()))\n            {\n                uncast_B->specB();\n            }\n        }\n\n        auto end = std::chrono::steady_clock::now();\n\n        auto diff = std::chrono::duration_cast<std::chrono::microseconds>(end - start).count();\n        std::cout << \" - merged array of shared_ptr with casting: \t\" << std::to_string(diff) << \"μs\" << std::endl;\n    }\n\n    {\n        auto start = std::chrono::steady_clock::now();\n\n        for (auto ptr : vec_container)\n        {\n            ptr.perf();\n        }\n\n        auto end = std::chrono::steady_clock::now();\n\n        auto diff = std::chrono::duration_cast<std::chrono::microseconds>(end - start).count();\n        std::cout << \" - array of container with iteration: \t\t\" << std::to_string(diff) << \"μs\" << std::endl;\n    }\n\n    {\n        auto start = std::chrono::steady_clock::now();\n\n        for (auto ptr : vec_container)\n        {\n            if (A *uncast_A = dynamic_cast<A *>(ptr.data.get()))\n            {\n                uncast_A->specA();\n            }\n            else if (B *uncast_B = dynamic_cast<B *>(ptr.data.get()))\n            {\n                uncast_B->specB();\n            }\n        }\n\n        auto end = std::chrono::steady_clock::now();\n\n        auto diff = std::chrono::duration_cast<std::chrono::microseconds>(end - start).count();\n        std::cout << \" - array of container with data casting: \t\" << std::to_string(diff) << \"μs\" << std::endl;\n    }\n}\n\nint main()\n{\n    // call();\n    perf();\n}\n\n// https://www.cppstories.com/2014/05/vector-of-objects-vs-vector-of-pointers/\n// g++ -o inheritance -Werror -Wfatal-errors -O3 -s -fexpensive-optimizations ./inheritance.cpp\n\n/*\nVectors size\n - vecA + vec_B: \t\t    20 000 000\n - vec_sptA + vec_sptB:     20 000 000\n - vec_sptBase:  \t\t    20 000 000\n - vec_container:  \t\t    20 000 000\n\nDurations:\n\nGood, but can't use polymorphism (heavy)\n - simple array of obj iteration: \t\t              1 μs  // pre optimisation\n - array of shared_ptr iteration: \t\t        543 048 μs\n\nMeh, polymorphism but slow for nothing on base function\n - merged array of shared_ptr iteration:        408 033 μs\n - merged array of shared_ptr with casting: \t659 349 μs\n\nSame, no gain of perf by extracting the base function\n - array of container with iteration: \t\t    403 188 μs\n - array of container with data casting: \t    638 731 μs\n*/

linkThreads

#include <iostream>\n#include <thread>\n\nstatic bool s_Finished = false;\n\n// Just print a line of text\nvoid DoWork() {\n\n\tusing namespace std::literals::chrono_literals;\n\n\tstd::cout << \"Function thread id=\" << std::this_thread::get_id() << std::endl;\n\n\twhile(!s_Finished) {\n\t\t// \n is performance wise better than endl, unless flushing of stream is required\n\t\tstd::cout << \"Working...\n\";\n\n\t\t// Prevent the thread to be CPU Usage 100% (if it print as fast as he can)\n\t\tstd::this_thread::sleep_for(1s);\n\t}\n}\n\nint main() {\n\tstd::cout << \"Main thread id=\" << std::this_thread::get_id() << std::endl;\n\t// This worker will just print Working as fast as it can until we press Enter\n\tstd::thread worker(DoWork);\n\n\t// When whe press Enter, set s_Finished to true and stop the function printing by the otehr thread\n\tstd::cin.get();\n\ts_Finished = true;\n\n\t// Tell the main thread to wait that the thread worker finish his task before it run the next ones\n\tworker.join();\n\n\tstd::cout << \"Finished.\" << std::endl;\n\t// Dont do cin.get() while the otehr thread is running\n\tstd::cin.get();\n\n\treturn 0;\n}

linkSFML

#include <SFML/Graphics.hpp>\n\nint main()\n{\n    // Create the main window\n    sf::RenderWindow window(sf::VideoMode(800, 600), \"SFML window\");\n\n    // Create a Rectangle shape to display\n    sf::RectangleShape rectangle(sf::Vectir2f(120,50)); // Width, Height\n    rectangle.setFillColor(sf::Color(150, 50, 250));\n    rectangle/setOutlineThickness(10);\n    rectangle.setOutlineColor(sf::Color::Red);\n    rectangle.setorigin(sf::Vector2f(100, 100));\n    rectangle.setPosition(100, 200);\n    rectangle.setRotation(30);\n\n    // Create a Circle shape to display\n    sf::CircleShape circle(50, 0); // Radius, Number of faces (0=circle, 3=triangle ...)\n\n    // Create a Triangle shape to display\n    sf::ConvexShape triangle;\n    triangle.setPointCount(3);\n    triangle.setPoint(0, sf::Vector2f(10,10));\n    triangle.setPoint(1, sf::Vector2f(20,20));\n    triangle.setPoint(2, sf::Vector2f(30,10));\n\n\n    // Create a graphical text to display\n    sf::Font font;\n    if (!font.loadFromFile(\"arial.ttf\"))\n        return EXIT_FAILURE;\n    sf::Text text(\"Text\", font, 50);\n\n    // Start display loop\n    while (window.isOpen())\n    {\n        // Process events\n        sf::Event event;\n        while (window.pollEvent(event))\n        {\n        \t// Close window: exit\n            if (event.type == sf::Event::KeyPressed)\n                system(\"pause\");\n            // Close window: exit\n            if (event.type == sf::Event::Closed)\n                window.close();\n        }\n        // Clear screen\n        window.clear(sf::Color::Black);\n\n        // Draw the rectangle\n        window.draw(rectangle);\n\n        // Draw the circle\n        window.draw(circle);\n\n\t\t// Draw the triangle\n        window.draw(triangle);\n\n        // Draw the string\n        window.draw(text);\n\n        // Update the window\n        window.display();\n\n\t\t// Set delay to update\n        sleep(milliseconds(10));\n    }\n\n}

","path":"sheets/languages-cpp","file":"sheets/languages/cpp"},{"meta":{"title":"C#","short":"Object-oriented programming language developed by Microsoft as part of its .NET initiative.","topic":"language c#"},"html":"

linkCheat Sheets

linkUsefull Informations

Official Documentation: MicrosoftCsharp

About Csharp

Type of Language: Procedural, Object-Oriented
Born in: 2000
Caracteristics: Microsoft plateforms language
Popularity: 6.5% (4th) src
Usefull for: software, mobile, web api…

linkTypes and Variables

PRIMITIVES

Name	Expression	Size	Min	Max
Boolean	`$foo = true;`	`1 bits`	0 (false)	1 (true)
Int	`$foo = 1234;`	`32+ bits`	-9.223e+15	9.223e+15
Float	`$foo = 1234;`	`32+ bits`	-9.223e+15	9.223e+15
Double	`$foo = 1234;`	`32+ bits`	-9.223e+15	9.223e+15

COMPLEX

Name	Expression	Size	Min	Max
DateTime	`$foo = true;`	`1 bits`	0 (false)	1 (true)
Point	`$foo = 1234;`	`32+ bits`	-9.223e+15	9.223e+15

CONVERSION

Char A = Char.Parse(string \"A\");\n\nChar output;\nif (Char.TryParse(string \"A\", out output)) {\n// Action\n}

linkInput Output

using System.Console;\n\nString name = Console.ReadLine();\nChar key = Console.ReadKey();\nConsole.WriteLine(\"Hello\" + name);

linkVariables, Tests and Loops

const INT32 MAJORITY = 18;

linkRandom numbers

linkArrays

STRINGS

String animal = \"Alpine newt\";\nanimal.Length; // 11\nanimal.Chars[0]; // 'A'\nanimal.ToLower; // \"alpine newt\"\nanimal.ToUpper; // \"ALPINE NEWT\"\nanimal.Trim(\"A\"); // \"lpine newt\"

ARRAYS

String[] days = new String[] { \"Monday\", \"Tuesday\", \"Wednesday\", \"Thursday\", \"Friday\", \"Saturday\", \"Sunday\" };\nforeach (String day in days) {\nConsole.WriteLine(day);\n}\n\nfor (int i=0; i<days.Length; i++) {\nConsole.WriteLine(days[i]);\n}\n\nArray.IndexOf(days, \"Wednesday\"); // 2 (first occurency)\nArray.LastIndexOf(days, \"Wednesday\"); // 2 (last occurency)\nArray.Reverse(days);\nArray.Sort(days);

LISTS

List <String> names = new List<String> { /* ... */ };\nforeach (String name in names) {\nname = name + \"s\";\n}\n\nfor (int i=0; i<names.Count; i++) {\nnames[i] = names[i] + \"s\";\n}\n\nnames.IndexOf(\"value\");\nnames.LastIndexOf(\"value\");\nnames.Reverse();\nnames.Sort();\n\nnames.Add(\"value\");\nnames.Insert(index, \"value\");\nnames.RemoveAt(index);

DATE

string date = \"01/01/2000\";\nDateTime dateA = DateTime.Parse(date);\nDateTime dateB = new DateTime(2017, 6, 30);

linkFunctions

linkClasses and Properties

METHODS AND CONSTRUCTOR

public class Person {\n/* private Property */\nprivate string name;\nprivate DateTime born;\n\n\t/* Public Property */\npublic string Name {\n\tget => this.name;\n\tset {\n\t\tif (value == null) {\n\t\t\tthrow.newArgumentException(\"Name can't be null\");\n\t\t} else {\n\t\t\tthis.name = value;\n\t\t}\n\t}\n}\n\n\t/* Public Constructor */\npublic Person(String pName) {\n\tName = pName;\n\tthis.born = DateTime.Now;\n}\n\n\t/* Method Definition */\npublic int GetAge() {\n\tint Age = DateTime.Now.Year - born.Year;\n\tif (born.Month > DateTime.Now.Month) {\n\t\tAge-=1;\n\t} else if (born.Month > DateTime.Now.Month) {\n\t\tif (born.Day > DateTime.Now.Day) {\n\t\t\tAge-=1;\n\t\t}\n\t}\n\treturn Age;\n}\n\n\t/* Method Overload */\npublic override string ToString() {\n\treturn \"\nName: \" + Name;\n}\n\n\t/* Redifine Operators*/\n\n\tpublic override bool Equals (object person) {\n\tif (person == null) { return false; }\n\tif (person.GetType() != this.GetType()) { return false; }\n\tPerson p = person as Person;\n\treturn this.Name == p.Name;\n}\n\n\tpublic static bool operator ==(Person a, Person b) {\n\treturn a.Equals(b);\n}\n\n\tpublic static bool operator !=(Person a, Person b) {\n\treturn !(a == b);\n}\n}\n\n/* Class Instanciation */\nstatic void Main(string[] args) {\n\nPerson person = new Person(\"Name\");\nperson.ToString();\n}

DEFAULT METHODS

object.ToString();
object.Equals(object);
object.GetHashCode();

ABSTRACT CLASS

An Abstract Classes cannot be instantiated, but can be very useful\nby creating different classes that inherit its properties to be sure\nof their homogeneity, and then be able to store them in common tables\nper instance.

abstract class Shape {\n\tpublic abstract int GetArea();\n}\n\nclass Square : Shape {\n\tint side;\n\tpublic Square(int nSide) { side = nSide; }\n\tpublic override int GetArea() { return side * side; }\n\n\tstatic void Main() {\n\t\tSquare square = new Square(12);\n\t\tConsole.WriteLine(\"Area of the square: \" +  square.GetArea());\n\t}\n}\n\nclass Circle : Shape {\n\tint radius;\n\tpublic Circle(int nRadius) { radius = nRadius; }\n\tpublic override int GetArea() { return 3.14159265 * radius * radius; }\n\n\tstatic void Main() {\n\t\tSquare square = new Square(12);\n\t\tConsole.WriteLine(\"Area of the square: \" +  square.GetArea());\n\t}\n}\n\n/* Class Instanciation */\nstatic void Main(string[] args) {\n\n\tList<Shape> shapes = new List<Shape>(); /* Array of the Abstract class, which of course will not contain any Shape, but Squares and Circles... */\n\tshapes.Add(new Square(10));\n\tshapes.Add(new Circle(5));\n\n\tfor (int i=0; i < shapes.Count; i++) {\n\t\tConsole.WriteLine(shapes[i].GetArea()); /* We can now call the method of the abstract class for every derivative instanciated */\n\t}\n}

linkTest Unit

using projectName;\n\nnamespace UnitTestNameProject {\n\n\t[Test Class]\n\tpublic class UnitTestClass {\n\n\t\t[Test Method]\n\t\tpublic void TestMethod() {\n\t\t\tObject obj = new Object( /* ...*/ );\n\t\t\tint value = 42; // Theorical result\n\t\t\tAssert.Equals(value, obj.Method());\n\t\t}\n\t}\n}\n\n/* Factorisation */\n[TestInitialize()]\npublic void init() {\nObject obj = new Object( /* ...*/ );\n}

ASSERTIONS

/* Values Assertion */\nAssert.Equals(valueA, valueB);\n\nAssert.IsTrue(/* ... */);\nAssert.IsFalse(/* ... */);\n\nAssert.Null(/* ... */);\nAssert.IsNotNull(/* ... */);\n\n/* Instances Comparison */\nAssert.AreEqual(A, B);\nAssert.AreNotEqual(A, B);\n\nAssert.AreSame(A, B);\nAssert.AreNotSame(A, B);

linkEnumerators

COSTS = new double[] { 10, 20, 30 };\npublic enum grade { A = 0, B = 1, C = 2 };\nint vGrade = (int)this.Grade;\ncost = COSTS[vGrade]

linkXAML

GUI DESIGN

The GUI Design is defined in App.xaml

<Window Title=\"Windows Title\" Width=\"640\" Height=\"480\" MinWidth=\"400\" MaxWidth=\"800\" ResizeMode=\"NoResize\" WindowsStartupLocation=\"CenterScreen\">\n<Grid>\n\t<Grid.ColumnDefinition />\n\t\t<ColumnDefinition Width=\"330\"/> <!-- Fixed Width -->\n\t\t<ColumnDefinition Width=\"*\"/> <!-- Auto Width -->\n\t</Grid.ColumnDefinition>\n\n\t<Menu>\n\t\t<MenuItem Header=\"_Menu\">\n\t\t\t<MenuItem Header=\"_SubMenu\" Click=\"SubMenuFunction\"/>\n\t\t</MenuItem>\n\t</Menu>\n\n\t<!-- GUI Definition -->\n\n\t<Button x:Name=\"Code_Name\" Content=\"\" HorizontalAlignment=\"left\" Height=\"200\" Margin=\"0,0,0,0\" Grid.Column=\"0\"/>\n\n</Grid>

BACK

The Code-Behin of the GUI is defined in the App.xaml.cs

public MainPage() {\n\tInitializeComponent();\n\n\t/* Generate a Button Grid */\n\tprivate Button[,] ButtonGrid;\n\n\tint GridHeight = 10;\n\tint GridWidth = 10;\n\n\tthis.ButtonGrid = new Button[GridWidth, GridHeight];\n\n\tgrille = new Grid();\n\tgrille.Width = 300;\n\tgrid.HorizontalAlignment = HorizontalAlignment.Left;\n\tgrid.VerticalAlignment = VerticalAlignment.Top;\n\n\tfor (int i=0; i < GridWidth; i++) {\n\t\tfor (int j=0; j < GridHeight; j++) {\n\t\t\tthis.ButtonGrid[i,j] = new Button();\n\t\t\tthis.ButtonGrid[i,j].Margin = new Thickness (5 + 32*i, 20 + 32*j, 0, 0);\n\t\t\tGrid.SetRow(this.ButtonGrid[i,j], 0);\n\t\t\tthis.grid.Childre.Add(this.ButtonGrid[i,j]);\n\t\t}\n\t}\n}

CUSTOM POPUP

public MyPopup(String text) {\n   \tInitializeComponent();\n   \ttexte.Text = text;\n}\n\nMyPopup popup = new MyPopup(\"text\");\npopup.ShowDialog();\npopup.Close();\n\nString popupName = popup.Name;\n\nMessageBox.Show(\"text\");\n\nSystem.Windows.Application.Current.Shutdown();

","path":"sheets/languages-csharp","file":"sheets/languages/csharp"},{"meta":{"title":"Java","short":"general-purpose object-oriented programming language, write once, run anywhere","topic":"language java"},"html":"

linkJavaFx

linkFirst Program

import javafx.application.Application;\nimport javafx.stage.Stage;\nimport javafx.scene.Scene;\nimport javafx.scene.layout.BorderPane;\nimport javafx.scene.control.Button;\n\n/*\nStructure: Stage > Scene > Nodes\n*/\npublic class MyApplication extends Application {\n\tpublic void start(Stage stage) {\n\t\tstage.setTitle(\"Application Title\");\n\t\tstage.setScene(createScene(stage));\n\t\tstage.show();\n\t}\n\tpublic Scene createScene(Stage stage) {\n\t\tBorderPane root = new BorderPane();\n\t\tButton button = new Button(\"Button Label\");\n\t\troot.setCenter(button);\n\t\treturn new Scene(root, 200, 100);\n\t}\n\tpublic static void main(String[] args) {\n\t\tlaunch();\n\t}\n}

linkPAC

linkElements

linkAgencement

import javafx.scene.layout.Hbox;\n\nHbox root = new Hbox();\nroot.getChildren().addAll(/* ... */);

import javafx.scene.layout.Vbox;\n\nVbox root = new Vbox();\nroot.getChildren().addAll(/* ... */);

import javafx.scene.layout.FlowPane;\n\nFlowPane root = new FlowPane(Orientation.HORIZONTAL);\nroot.setRowValignment(VPos.TOP);\nroot.setColumnHalignment(HPos.CENTER);\nroot.getChildren().addAll(/* ... */);

import javafx.scene.layout.TilePane;\n\nTilePane root = new TilePane(Orientation.HORIZONTAL);\nroot.getChildren().addAll(/* ... */);

import javafx.scene.layout.GridPane;\n\nGridPane root = new GridPane();\nroot.addRow(0, /* Node, Node,... */);\nroot.addColumn(3, /* Node, Node,... */);\nroot.add(/* Node */, 1, 2);\nroot.add(/* Node */, 4, 0, 1, 2);

import javafx.scene.layout.AnchorPane;\n\nAnchorPane root = new AnchorPane();\nroot.getChildren().addAll(/* ... */);\nroot.setTopAnchor(/* Node */, 40.0);\nroot.setRightAnchor(/* Node */, 0.0);\nroot.setBottomAnchor(/* Node */, 0.0);\nroot.setLeftAnchor(/* Node */, 0.0);

import javafx.scene.layout.StackPane;\n\nStackPane root = new StackPane();\nroot.getChildren().addAll(/* ... */);

import javafx.scene.layout.BorderPane;\n\nBorderPane root = new BorderPane();\nroot.setTop(/* ... */);\nroot.setBottom(/* ... */);\nroot.setLeft(/* ... */);\nroot.setRight(/* ... */);\nroot.setCenter(/* ... */);

linkComponents

","path":"sheets/languages-java","file":"sheets/languages/java"},{"meta":{"title":"JavaScript","short":"High-level, dynamically-typed language, easy of use and flexible","topic":"language js"},"html":"

linkProgramming in JS

linkFirst Program : webpage

<!DOCTYPE html>\n\n<html>\n\t<head>\n\t\t<meta charset=\"UTF-8\" />\n\n\t\t<title>Space Invader</title>\n\n\t\t<link rel=\"stylesheet\" type=\"text/css\" href=\"style.css\" />\n\t</head>\n\n\t<body></body>\n</html>\n\n<script type=\"text/javascript\">\n\t/*\n        We must wait that the web page is fully loaded before beggining\n        to access and edit it's components (We wait DOMContentLoaded)\n    */\n\tdocument.addEventListener('DOMContentLoaded', function () {\n\t\t/* \n            We can read the elements in the page with selectors.\n            We store it into a variable with: let v = ...  \n        */\n\t\tlet body = document.querySelector('body');\n\n\t\t/*\n            You can use console.log(...) to display text or objects \n            in the web browser console (Ctrl + Shift + J for Chrome)\n        */\n\t\tconsole.log('Document loaded');\n\t});\n</script>\n\n<style type=\"text/css\">\n\t* {\n\t\tpadding: 0px;\n\t\tmargin: 0px;\n\t}\n</style>

linkVariables

JavaScript is Dynamically typed. There is ‘types’ but they are computed on the go, you cannot statically declare the type of a\nvariable. That’s one of the reasons why JS is not a fast language.

TypeScript has been created to fix this by enabling the declaration of the type, but it’s ony a pre-check, because in the end it’s also compiled in JS.

/* Declare with LET */\nlet a = 'A' /* This is my default declaration for the variables */\nlet b /* You can also declare a variable without assigning it a value */\nlet c = 15 /* The variable type is automaticly computed... */\nc = 'test' /* ...but no problem for assigning it everithing, no parse needed*/\n\n/*\n    Let is a local definition, you can only access it in the current bloc.\n    To create global variables, just declare them outside the main bloc.\n*/\nfunction() {\n    let d = 'my local variable'\n    console.log(d) /* 'my local variable' : we are inside the bloc */\n}\nconsole.log(d) /* undefined : we are outside the bloc were d is defined */\n\n/* Declare with VAR */\n\n/*\n    Var is the same as Let but it's permit to declare variables in the Global\n    condext: it attach the var to the 'window' object instead of the bloc\n*/\nfunction() {\n    var e = 'my global variable'\n    console.log(e) /* 'my global variable' */\n}\nconsole.log(e) /* 'my global variable' */\nconsole.log(window.e) /* 'my global variable' */\n\n/* Declare with CONST */\nconst NUMBER = 1 /* const must be defined when declarated and cannot be edited */

linkConsole Log

Console log display the items passed by parameters

/* Text */\nconsole.log('test here')\n\n/* Array */\nconsole.log([{ id: 0, name: 'A'}, { id: 1, name: 'B'}, { id: 2, name: 'C'}])\n(3) [{…}, {…}, {…}]\n    > 0: {id: 0, name: \"A\"}\n    > 1: {id: 1, name: \"B\"}\n    > 2: {id: 2, name: \"C\"}\n    length: 3\n    > __proto__: Array(0)\n\n/* Text */\nconsole.log('Insert %s here','text')\n/*\n    You can interpolate values with flags:\n    %s (string)\n    %d (decimal)\n    %j (json)\n    %O (object with depth of 4)\n    %o (object with depth of 2)\n*/\n\nconsole.error() /* For errors */\nconsole.dir() /* For directories */\nclass Console /* Create a console object */

linkTests

if (/* Condition */) {\n    /* Code */\n} else if (/* Condition */) {\n    /* Code */\n} else {\n    /* Code */\n}

linkLoops

for (let i = 0; i < 10; i++) {\n    /* 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 */\n}\n\ndo {\n    /* Code */\n} while (/* Condition */)\n\nwhile (/* Condition */) {\n    /* Code */\n}\n\nlet items = ['A','B','C']\n\nfor (let i in items) {\n    console.log(i) /* 0, 1, 2 */\n    items[i] /* A, B, C */\n}\n\nfor (let i of items) {\n    console.log(i) /* A, B, C */\n}

linkFunctions

/* Parameters with default values become optionnal */\nfunction print(parameter = 0) {\n    console.log(parameter)\n    return true /* You can choose to return something or not */\n}\n\nprint() /* 0 */\nprint('test') /* 'test' */\n\n/* You can also declare functions like this */\nlet func = () => 'test' /* this function just return 'test' */\nconsole.log(func()) /* 'test' */\n\nlet func = (parameterA, parameterB ...) => {\n    /* Code */\n}

linkSelectors

console.log(document); /* reference all the informations on the current page */\n\n/* Get elements with querySelector */\nlet body = document.querySelector('body'); /* We select the html element body */\ndocument.querySelector('#idObject'); /* We cans select object like in css, with the id... */\ndocument.querySelector('.classObject'); /* ... and the class, but it only return the first */\ndocument.querySelectorAll(\n\t'.classObject'\n); /* To get all items in an array, we use querySelectorAll */\n\n/* Get elements with getElementById */\ndocument.getElementById('idObject'); /* We can get the first*/\n\n/* Get elements with getElementByClassName */\ndocument.getElementByClassName(\n\t'classA classB ...'\n); /* We get the array of all elements that have both classes */\ndocument.getElementByClassName('class')[0]; /* ... to get the first element of the list */

linkEvents

setTimeout(function() { /* Code */ }, 5000) /* After 5000ms */\nsetInterval(function() { /* Code */ } 3000) /* Every 3000ms */\n\nelement.addEventListener('click', function(event) { /* Code */ })\n\nfunction().then(function(data) { /* Code */ }).catch(function(error) { /* Code */ })\n\nasync function asynchrone() {\n    let value = await function() { /* Code */ }\n    return value\n}\n\ntry { /* Code */ } catch (error) { /* Code */ }

linkAjax

function Send(url, params, callback) {\n\tlet xhr = new XMLHttpRequest();\n\txhr.open('POST', url, true);\n\txhr.responseType = 'json';\n\txhr.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');\n\n\txhr.onreadystatechange = function () {\n\t\tif (xhr.readyState === XMLHttpRequest.DONE && xhr.status === 200) {\n\t\t\tcallback(xhr.response);\n\t\t}\n\t};\n\tlet s = '';\n\tfor (let attr in params) s += attr + '=' + params[attr] + '&';\n\txhr.send(s);\n}\n\nfunction Get(url) {\n\treturn new Promise(function (resolve, reject) {\n\t\tlet xhr = new XMLHttpRequest();\n\t\txhr.open('GET', url);\n\t\txhr.onload = function () {\n\t\t\tlet data = JSON.parse(xhr.responseText);\n\t\t\tresolve(data);\n\t\t\t//console.log(data[0]);\n\t\t};\n\t\txhr.onerror = reject;\n\t\txhr.send();\n\t});\n}

linkNodeJs

“NodeJs is an open source cross-plateform back-end JavaScript\nEnvironment that execute javaScript outside a web browser. It was build\nin 2009 in JavaScript and in C/C++ where JavaScript was performing too\nslow. Node use V8 to compile JS source code to native machine code at\nruntime.

Download Node: https://nodejs.org/en/download/

node --version\n\nnode\n> 2 + 2\n4\n> .help\n> .exit\n\nnode file.js

Node Package Manager (npm)

npm install package\nnpm view package\nnpm search package\nnpm help\nnpm version\nnpm list\nnpm update /* update all packages */\nnpm init /* Tool to initialize package.js */\n\nnpm test\nnpm start\nnpm run serve

Node Path System (path)

const path = require('path')\nconsole.log('src' + path.sep + 'file')\nconsole.log(path.join('src','file'))\n\npath.basename(path) /* file name */\npath.dirname(path) /* folder name */\npath.extname(path) /* file extention */\npath.isAbsolute(path) /* false if relative */\npath.relative(pathA, pathB) /* return relative path to go from A to B */\npath.resolve('path',step,step,...) /* return the absolute path after completing the steps */

Node File System (fs)

const fs = require('fs')\nconst path = require('path')\nconst filename = path.join(__dirname, 'file\")\n/*\n    __dirname: current repertory\n    __filename: current file\n*/\n\nfs.readFile(filename, (err, res) => {\n    console.log(String(res))\n})\n\nfs.readDir(path, (err, res) => {\n    console.log(res) /* files and subfolders */\n})\n\nfs.mkdir(path, (err) => {}) /* make folder */\nfs.copyFile(file, path, (err) => {}) /* copy file */\nfs.rename(file, new, (err) => {}) /* rename file/folder */\nfs.rmdir(path, (err) => {}) /* remove folder if empty */\nfs.unlink(path, new, (err) => {} /* remove file*/

Server HTTP (http)

const http = require('http');\nconst server = http.createServer();\nserver.listen(4000, 'localhost');\n\nserver.on('request', (req, res) => {\n\tres.setHeader('Content-Type', 'text/html; charset=utf-8');\n\n\tres.write('Hello world');\n\tres.end();\n});

linkJest

Unit Testing

npm install jest --save-dev\n\nmkdir src/utils/__tests__\ncd src/utils/__tests__\necho.>Element.spec.js\n\n/* Run tests */\nnpm test --coverage

package.json\n\n\"scripts\": {\n    \"test\": \"jest\"\n},\n\"jest\": {\n    \"collectCoverage\": true,\n}

src\n└───test\n    ├───smoke\n    └───unit\n        ├───coverage\n        └───specs // units tests here

import Element from 'src/element' /* With Babel*/\nconst Element = required('src/element') /* Without Babel*/\n\njest.mock('library') /* if the element use an external library */\n\n/* Describle contain one or more related tests */\ndescrible('description string', () => {\n\n    /* Before each test */\n    beforeEach(() => {\n        /* Environment setup */\n        process.env = {\n            /* Environment variables setup */\n        }\n    })\n\n    /* After each test */\n    afterEach(() => {\n        /* Clean things */\n    })\n\n    /* You then describle your tests with: test or it (alias) */\n    it('test description', () => {\n        /* Variables Setup */\n        const input = [\n            { id:0, name:'A' },\n            { id:0, name:'B' },\n            { id:0, name:'C' }\n        ]\n        const output = [{ id:0, name:'B' }]\n        const spy = jest.spyOn(object, 'function')\n\n        /* Function Test */\n        // [...]\n\n        /* Assertions */\n        expect(/*...*/).toEquals(output) /* Result */\n        expect(spy).toHaveBeenCalledTimes(1) /* Spy */\n        expect(/*...*/).toMatch('Error\") /* Errors */\n    })\n\n    it('async test description', async () => {\n        /* Here we test with an async function */\n    })\n}

linkCypress

Integration Testing

install global cypress: npm install -g cypress\n\ncypress run -P . --config video=false --spec '**/integration/test.spec.js' -b chrome\ncypress open -P .

src\n└───cypress\n    ├───support\n    |   ├───index.js\n    |   └───commands.js\n    └───tests\n        ├───smoke\n        └───integration\n            └───test.spec.js // integration tests here

support / index.js;\n\nCypress.on('window:before:load', function (window) {\n\tconst original = window.EventTarget.prototype.addEventListener;\n\n\twindow.EventTarget.prototype.addEventListener = function () {\n\t\tif (argument && argument[0] === 'beforeunload') {\n\t\t\treturn;\n\t\t}\n\t\treturn original.apply(this, arguments);\n\t};\n\n\tObjet.defineProperty(window, 'beforeunload', {\n\t\tget: function () {},\n\t\tset: function () {}\n\t});\n});

support / commands.js;\n\n//<button type=\"button\" data-test=\"mybutton\">Button</button>\n\nCypress.Commands.add('SelectMyButton', () => {\n\treturn cy.get('[data-test=\"mybutton\"]');\n});\n\nCypress.Commands.add('ClickMyButton', () => {\n\tcy.SelectMyButton().click();\n});

integration / test.spec.js;\n\ndescrible('Tests description', function () {\n\tconst BUTTON_CLICKED = 'clicked';\n\n\tbeforeEach(() => {\n\t\t/* ... */\n\t});\n\tafterEach(() => {\n\t\t/* ... */\n\t});\n\n\tit('Test description', function () {\n\t\tcy.ClickMyButton();\n\t\tcy.contains(BUTTON_CLICKED);\n\t});\n\n\t/* ... */\n});

linkJS-BUNDLING

linkComparison

linkFor CLI tools

Name	Note	Free license	Mainained	Binaries
pkg	Node bundler	✅ MIT	✅ Active	v18 x64-86
nexe	Node bundler	✅ MIT	✅ Active	v16 x64-86
enclose	Node bundler	❌ EULA	❌ Deprecated	v6 x64
node-packer	Node bundler	✅ MIT	❌ No (2y)
deno-build	Deno compiler	✅ MIT	✅ Active

linkFor GUI tools

Name	Note	Free license	Mainained	Binaries
nwjs	Chromium bundler	✅ MIT	✅ Active	v18 x64-86
electron	Chromuim bundler	✅ MIT	✅ Active
tauri	Rust bundler	✅ MIT	✅ Active
app-image	Packager	✅ MIT	✅ Active

linkPkg

1. Bundles the application with a custom v8 script compiler into a snapshot
1. Downloads the node source (or a prebuilt binary)
1. Applies arbitrary source patches
1. Maybe compiles downloaded source
1. Appends snapshotted output to the end of the binary
1. Snapshot (cachedData from v8) is loaded/run when binary executes.

from https://github.com/vercel/pkg/issues/42

“Pkg hacked fs.* API’s dynamically in order to access in-package files, whereas Node.js Compiler leaves them alone and instead works on a deeper level via libsquash. Pkg uses JSON to store in-package files while Node.js Compiler uses the more sophisticated and widely used SquashFS as its data structure.”

pkg:

a lot of configuration possible (see usage settings)
best support for distributed node binaries
support multiple builds at a time
configuration in json or by command line (see config)
option to build the node binaries ourself with --build
don’t work well with ES6 modules (use require) => or see nexe

linkFile System

“Hence, in order to make use of a file collected at packaging time (require a javascript file or serve an asset) you should take __filename, __dirname, process.pkg.defaultEntrypoint or require.main.filename as a base for your path calculations.

For javascript files you can just require or require.resolve because they use current __dirname by default. For assets use path.join(__dirname, ``'../path/to/asset')”\nfrom https://github.com/vercel/pkg#snapshot-filesystem

linkNode binaries fetcher

Supported:

alpine, linux, macox, windows (x32/64)
node <= v18

linkDetails

Building in DEBUG mode:

pkg -o dist/panorama.exe src/index.js --debug > build_log.txt

[cernbox build_log.txt]

1.1. Navigate dependandancies from the scipt input and add them to the queue

[debug] Content of /home/user/Documents/Projects/panorama/node_modules/nodemon/package.json is added to queue.\nIt was required from /home/user/Documents/Projects/panorama/src/index.js\n\n[debug] Bytecode of /home/user/Documents/Projects/panorama/node_modules/nodemon/lib/nodemon.js is added to queue.\nIt was required from /home/user/Documents/Projects/panorama/src/index.js\n...

1.2. Resolve ambiguous paths

[debug] Path.resolve('.') is ambiguous\n/home/user/Documents/Projects/panorama/src/system.js\nIt resolves relatively to 'process.cwd' by default, however\nyou may want to use 'path.dirname(require.main.filename)'

1.3. Directories and stats added to the VFS

[debug] Directory /home/user/Documents/Projects/panorama/node_modules/jsdom/lib/jsdom/living is added to queue.

1.4. Convert to bytecode and add

[debug] The file was included as bytecode (no sources)\n/home/user/Documents/Projects/panorama/src/index.js\n\nThe file was included as DISCLOSED code (with sources)\n/home/user/Documents/Projects/panorama/node_modules/nodemon/package.json

“By default, your source code is precompiled to v8 bytecode before being written to the output file”\nfrom https://github.com/vercel/pkg#bytecode-reproducibility

1.5 Merge required sources

> [debug] files & folders deduped =\n  index.js\n  inputs.js\n  system.js\n  parsing.js

With config

[debug] Targets:\n  [\n  {\n    "nodeRange": "node16",\n    "platform": "linux",\n    "arch": "x64",\n    "output": "/home/user/Documents/Projects/panorama/dist/panorama.exe",\n    "forceBuild": false,\n    "fabricator": {\n      "nodeRange": "node16",\n      "platform": "linux",\n      "arch": "x64",\n      "binaryPath": "/home/user/.pkg-cache/v3.4/fetched-v16.16.0-linux-x64"\n    },\n    "binaryPath": "/home/user/.pkg-cache/v3.4/fetched-v16.16.0-linux-x64"\n  }\n]

Running the binary

DEBUG_PKG=1 ./panorama

[cernbox run_log.txt]

------------------------------- virtual file system\n/snapshot\n  panorama                                 8993610\n    src                                      10864\n      index.js                                1607\n      inputs.js                               1992\n      system.js                               2778\n      parsing.js                              4487\n    node_modules                           8993610\n      nodemon                               125479\n        package.json                          2189\n        lib                                  85174\n          nodemon.js                          8777\n          version.js                          2465\n          spawn.js                            1893\n          monitor                            43382\n            index.js                            82\n            run.js                           16493

Building without including sources as bytecode

...\n--public             speed up and disclose the sources of top-level project\n--no-bytecode        skip bytecode generation and include source files as plain js\n...

“Specifying --no-bytecode will fail if there are any packages in your project that aren’t explicitly marked as public by the license in their package.json.”\nfrom https://github.com/vercel/pkg#other-considerations

linkNew simple js project specified as OS (no dependancies)

index.js

function main() {\n    console.log("Hello world")\n}\n\nmain()

package.json

{\n  "name": "decompiled",\n  "version": "1.0.0",\n  "description": "",\n  "main": "index.js",\n  "scripts": {\n    "test": "node index.js",\n    "build": "pkg --public --no-bytecode index.js --debug -o dist/decompiled"\n  },\n  "author": "",\n  "license": "ISC",\n  "dependencies": {\n    "pkg": "^5.8.0"\n  }\n}

/!\\ MUST ADD BOTH --no-bytecode AND --public\notherwise Error! --no-bytecode and no source breaks final executable see https://github.com/vercel/pkg/issues/1139

… still not working

$\"screenshot\"$

linkSome readable parts

$\"screenshot\"$

from decompiled linux binaries

?	node binaries	?	?	code ?	modules

linkNexe

1. Bundles the application if desired using webpack.
1. Downloads node source (or a prebuilt binary)
1. Adds your application bundle as a native module (like fs, http, path etc)
1. Applies arbitrary source patches.
1. Maybe compiles downloaded source
1. Inserts bundle into pre-sized binary
1. Code is run as main when executable is run (instead of the repl)

Nexe does not support dynamic require because of its use of browserify, whereas Node.js Compiler supports all kinds of require including require.resolve.

https://github.com/nexe/nexe/issues/529

Nexe is a tool for compiling node. You can apply arbitrary patches and build plugins for repeatable patterns to that end. ie. You could make a plugin and or patch for nexe that bypasses the nexe application bundler and uses the same approach as pkg.

Application Bundling (just different approaches):

nexe uses a virtual filesystem (similar to tools like asar for electron) and module analysis to include your applications files and dependencies
pkg uses module analysis, and whitelists to create a V8 snapshot and load (“compile”) your application scripts.

Why use nexe ?

You need to have additional customizations to node (eg more builtin or native modules, C++ patches).
You want to codesign the executable. By bypassing the built in bundler (with a patch) you can create an application executable that can be signed/verified.
You want to add an icon (there are lots of ways to accomplish this, but code is usually the best way)
You want to extend it (plugin or patch) to provide a repeatable system for creating a specific type of application. Eg. a windows service or linux daemon.
Its hosted builds are created with 100% OSS.
It allows the JS engine to recompile in the future if it made bad predictions for hot code paths. (since it uses unchanged source, vs a snapshot. (This point is less relevant with the newer interpreter features)
It provides pre-built versions for any node version.

linkEnclose

http://enclosejs.com/

JavaScript code is transformed into native code at compile-time using V8 internal compiler. Hence, your sources are not required to execute the binary, and they are not packaged.
Optimized native code can be generated only at run-time, using information collected at run-time. Without that information EncloseJS can generate only “unoptimized” code. It runs about 2x slower, than optimized one.
Also, Node.js code is put inside the executable (along with your code) to support Node.js API for your application at run-time. This increases output file size.
So, this is not that static compilation we used to know. But nevertheless you get fully functional binary without sources. Also, performance and file size overhead are vectors of future work.

linkNode-packer

https://speakerdeck.com/pmq20/node-dot-js-compiler-compiling-your-node-dot-js-application-into-a-single-executable?slide=5

linkNwjs

https://github.com/nwjs/nw.js/wiki/How-to-package-and-distribute-your-apps

https://www.sitepoint.com/cross-platform-desktop-app-nw-js/

https://stackoverflow.com/questions/8173232/how-to-make-exe-files-from-a-node-js-app

1. Zip up all your files, with a package.json in the root
1. Change the extension from .zip to .nw
1. copy /b nw.exe+app.nw app.exe

linkElectron

linkAsar

Asar uses JSON to store files information while Node.js Compiler uses SquashFS. Asar keeps the code archive and the executable separate while Node.js Compiler links all JavaScript source code together with the Node.js virtual machine and generates a single executable as the final product.

linkTauri

https://github.com/tauri-apps/tauri

Detail	Tauri	Electron
Installer Size Linux	3.1 MB	52.1 MB
Memory Consumption Linux	180 MB	462 MB
Launch Time Linux	0.39s	0.80s
Interface Service Provider	WRY	Chromium
Backend Binding	Rust	Node.js (ECMAScript)
Underlying Engine	Rust	V8 (C/C++)
FLOSS	Yes	No
Multithreading	Yes	Yes
Bytecode Delivery	Yes	No
Multiple Windows	Yes	Yes
Auto Updater	Yes	Yes1
Custom App Icon	Yes	Yes
Windows Binary	Yes	Yes
macOS Binary	Yes	Yes
Linux Binary	Yes	Yes
iOS Binary	Soon	No
Android Binary	Soon	No
Desktop Tray	Yes	Yes
Sidecar Binaries	Yes	No

linkDeno-build

https://deno.land/manual/tools/compiler

linkAppImage

AppImage supports only Linux with a kernel that supports SquashFS, while Node.js Compiler supports all three platforms of Linux, macOS and Windows, meanwhile without any special feature requirements from the kernel.

https://appimage.org/

https://docs.appimage.org/introduction/motivation.html

https://docs.appimage.org/introduction/software-overview.html#ref-appimagekit

","path":"sheets/languages-js","file":"sheets/languages/js"},{"meta":{"title":"PHP","short":"dynamically-typed, interpreted language for building server-side web applications","topic":"language php"},"html":"

linkCheat Sheets

linkUsefull Informations

Official Documentation: https://www.php.net/docs.php

About PHP

Type of Language: Imperative, Object-Oriented
Born in: 1994
Caracteristics: Simple, permissive, html imbedded
Popularity: 5.85% (5th) src
Usefull for: website backend, database linking

linkTypes and Variables

variable typing is automatic in PHP

Name	Expression	Size	Min	Max
Boolean	`$foo = true;`	`1 bits`	0 (false)	1 (true)
Int	`$foo = 1234;`	`32+ bits`	-9.223e+15	9.223e+15
Float/Double	`$foo = 1.24;`	`32+ bits`	accuracy 1.11e-16
String	`echo 'test';`	`32+ bits`	64-bits => no restriction, else\n1.6e+10

It’s also possible do define the type like $foo = (double)4; or like\nsettype($foo,'double');

linkInput Output

   <?php\n   \t$age = 18;\n   \tvar_dump($age); // => int(18)\n   \techo gettype($age); // => integer\n\n   \tdefine(\"MAX\",10);\n   \techo('he is '.$age.'years old');\n   \t$input = trim(fgets(STDIN));

linkVariables, Tests and Loops

linkTESTS

<?php\n\nif (Condition) {\n  // Action\n}\n\nif (Condition) {\n  // Action\n} elseif (Condition) {\n  // Action\n} else {\n  // Action\n}\n\nif(Condition)\n  // Action\n\n($a == $b); // test equality of value ($a === $b); // test\nequality of value AND type

linkSWITCH

<?php\n\nswitch (variable) {\n  case 1: // Action\n    break;\n\n  case 2: // Action\n    break;\n\n  case 3: // Action\n    break;\n}

linkLOOPS

<?php\n\nfor ($i=0; $i < 10; $i++) {\n  // Action\n}\n\ndo {\n  // Action\n} while($i > 0);\n\nwhile ($i > 0) {\n  // Action\n}\n\nforeach ($items as $item) {\n  // Action\n}

You can use break; to stop a loop.

linkRandom numbers

<?php\n\ndefine(\"MIN\", 0); define(\"MAX\", 100);\n\n$alea = rand(MIN,MAX); // alias of mt_rand(MIN,MAX) since PHP

linkArrays

<?php\n\n$table = array(\"E1\"=>0, \"E2\"=>6, \"E3\"=>5);\n$table['E1'] = 10; $table['E2'] = 13;\n$table['V1'] = 5;\n\necho($table['E1']); // 10\n\nforeach ($table as $key => $value) {\n\necho (\"$key : $value n\");\n\n}\n\nfor($i=0; $i<count($table);$i++) {\n\necho $test[$i;]\n\n}\n\nprint_r($table);\n\n/* Array ( [E1] => 10 [E2] => 13 [E3] => 5 [V1] => 5 ) */\n\n$test = array(10, 15, 20); count($test); // 3

linkARRAYS OPERATORS

<?php\n\n$array_a = array(...); $array_b = array(...);\n\n$array_a + $array_b // union of a and b\narray_merge($array_a, $[array]()) // addition of items\narray_intersect($array_a, $[array]()) // intersection of items\n\nmin($array_a); // return the min elem\nmax($array_a); // return the max elem\narray_sum($array_a, $array_b); // return the sum of elem\nin_array(\"test\", $array_a); // search and return true/false\narray_search(\"test\", $array_a); // search and return the position\narray_shift($array_a); // extract the first value\narray_pop($array_a); // extract the last value\n\necho(round(6.1234, 2)); // 6.12 echo(pow(5,2)); // 25\n\narray_slice($array,2,1);

linkSTRINGS

<?php\n\n$string = 'my String'; echo('length: ' . strlen($string));\n// length: 9\n\necho('substr 0 7: ' . substr($string, 0, 7)); // substr 0 7: my Stri\n\necho('substr 1 1: ' . substr($string, 2, 2)); // substr 1 1: y\necho('substr 1: ' . substr($string, 1)); // substr 1: y String\necho('strpos S: ' . strpos($string, \"S\")); // strpos S: 3 (First occurence)\necho('strpos s: ' . strpos($string, \"s\")); // strpos s: false (Case sensitive)\necho('stripos s: ' . stripos($string, \"s\")); // stripos s: 3 (Not case sensitive)\necho('strrpos s: ' . strrpos($string, \"s\")); // strrpos s: 3 (Last occurence)\n\necho('lower: ' . strtolower($string)); // lower: my string\necho('upper: ' . strtoupper($string)); // upper: MY STRING\n\necho('first maj: ' . ucfirst($string)); // first maj: My String\necho('first min: ' . lcfirst($string)); // first min: my string\n\nexplode(\" \", $chain);

linkFILTER

<?php\n\nfilter_var($mail, FILTER_VALIDATE_EMAIL); $verification =\npreg_match($pattern, $string);

filter table:

`$`	end chain
`^`	begin chain
`.`	anything
`1`	exact number
`[a-z]`	chars
`[^b]`	not char

linkFOLDERS

<?php\n\n$handle = fopen(\"file.txt\",\"r\"); // pointer or false if\n($handle) {\n  while ($buffer = fgets($handle,2) != false) {\n  // return the line of a defined size\n  echo $buffer;\n  }\n}\n\nfwrite($handle, $string); fclose($handle);\n\nfile($filename [, FILE_IGNORE_NEW_LINES /\nFILE_SKIP_EMPTY_LINES]); // return file in array

options:

`r`	read from beggining
`r+`	writing from end
`w`	reset and write
`a`	reate or write from end

linkDATE

<?php\n\ndate_default_timezone_set('Europe/Paris');\ndate('Y')/date('m')/date('d');

linkFunctions

<?php\n\nfunction say($text[, $language=\"EN\"]) {\n\necho($text); return $language;\n\n}

linkEmbedded PHP

linkPost/Get

linkFORM

<form id=\"inscription\" method=\"post\" action=\"form.php\">\n\t<p>\n\t\t<label for=\"name\">Name:</label>\n\n\t\t<input type=\"text\" name=\"name\" id=\"name\" />\n\t</p>\n\n\t<input type=\"submit\" name=\"validate\" id=\"validate\" value=\"Send\" />\n</form>

linkText Input

value: displayed value
size: handler size
name: datas in php
placeholder: information
maxlength: max enabled
title: hovering info
required: needed to validate
pattern =“^[A-Za-z]+$”

linkTextArea Input

<textarea name=\"area\" id=\"area\" rows=\"10\" cols=\"10\"> default text </textarea>

linkRadio Input

value: 0 or 1
checked: default

linkCheckbox Input

name=“array[]”

linkSelect Input

<select name=\"departement\" id=\"departement\">\n\t<option value=\"choice A\">Choice A</option>\n\n\t<option value=\"choice B\">Choice B</option>\n\n\t<option value=\"choice C\">Choice C</option>\n</select>

linkSpecial Inputs

url
email
number
tel
date
time
search
color
range

linkFieldSet

<fieldset>\n\t<legend>Legend</legend>\n\n\t<!-- FORM -->\n</fieldset>

linkDatas

<?php\n\nprint_r($_POST); echo (\"Hello \".$_POST[\"name\"]);\n\nif (isset($_POST[\"sports\"] as $sport)) {\n\necho \"<ul>\"; foreach ($_POST[\"sports\"] as $sport)\n{ echo \"<li> $sport </li>\"; } echo \"</ul>\";\n\n}

linkInclude in same page

<?php\n\nif (!empty($_POST[])) {\n\ninclude_once(\"file.php\");\n\n}

linkDynamic variable

<?php\n\n$names = array('name','surname');\n\nforeach ($names as $name) {\n\n$$name = $_POST[$name];\n\n}\n\necho $name; // instead of echo $_POST[\"name\"]; echo\n$surname;

","path":"sheets/languages-php","file":"sheets/languages/php"},{"meta":{"title":"Analysis","short":"Derivative, factorial, modulo and prime numbers","topic":"maths analysis"},"html":"

linkDerivative

TODO;

linkFactorial

// factorial : https://en.wikipedia.org/wiki/Factorial\n// binomial coefficient : https://en.wikipedia.org/wiki/Binomial_coefficient\n\nfactorial = (n) => (n == 0 ? 1 : n * factorial(n - 1));\nbinomial = (k, n) => {\n\tlet a = 1;\n\tlet b = 1;\n\n\twhile (k > 0) {\n\t\ta *= n - k + 1;\n\t\tb *= k;\n\t\tk--;\n\t}\n\n\treturn a / b;\n};\n\n// !3 = 6\nconsole.log('!3 =', factorial(3));\n\n// !10 = 3628800\nconsole.log('!10 =', factorial(10));\n\n// (10 20) = 184756\nconsole.log('(10 20) =', binomial(10, 20));\n\n// (3 7) = 35\nconsole.log('(3 7) =', binomial(3, 7));

linkModulo

// Positive modulo : https://en.wikipedia.org/wiki/Modulo_operation\n// For every input I and N, we want to assert that the result of the modulo is a positive number.\n\nconst I = -62;\nconst N = 34;\n\npositive_modulo = (i, n) => ((i % n) + n) % n;\n\n// mod = -28\nconsole.log('mod =', I % N);\n\n// pos = 6\nconsole.log('pos =', positive_modulo(I, N));

linkPGCD

// pgcd : https://en.wikipedia.org/wiki/Greatest_common_divisor\n// ppcm : https://en.wikipedia.org/wiki/Least_common_multiple\n\npgcd = (a, b) => (b === 0 ? a : pgcd(b, a % b));\nppcm = (a, b) => (a * b) / pgcd(a, b);\n\n// pgcd 25 10 = 5\nconsole.log('pgcd 25 10 =', pgcd(25, 10));\n\n// ppcm 25 10 = 50\nconsole.log('ppcm 25 10 =', ppcm(25, 10));\n\n// pgcd 25 30 10 15] = 5\nconsole.log(\n\t'pgcd 25 30 10 15] =',\n\t[25, 30, 10, 15].reduce((acc, val) => pgcd(acc, val))\n);\n\n// ppcm 25 30 10 15 = 150\nconsole.log(\n\t'ppcm 25 30 10 15 =',\n\t[25, 30, 10, 15].reduce((acc, val) => ppcm(acc, val))\n);

linkPower

// Exponentiation : https://en.wikipedia.org/wiki/Exponentiation\n\nconst I = 12;\nconst N = 7;\n\ndiv = (i, n) => Math.floor(i / n); // integer division\n\n// O(n) power function\npow = (i, n) => (n == 0 ? 1 : i * pow(i, n - 1));\n\n// O(log(n)) power function\npow_opt = (i, n, DIVIDER = 2) => {\n\tpow_rec = (i, n) => {\n\t\tif (n == 1) return i;\n\n\t\tconst remain = n % DIVIDER;\n\t\tconst mult = remain == 0 ? div(n, DIVIDER) : div(n - 1, DIVIDER);\n\n\t\tconst rec = pow_opt(i, mult);\n\t\tlet val = rec;\n\t\tfor (let x = 0; x < DIVIDER - 1; x++) val *= rec;\n\t\tfor (let x = 0; x < remain; x++) val *= i;\n\n\t\treturn val;\n\t};\n\n\tif (n == 0) return 1; // zero pow\n\tif (n > 0) return pow_rec(i, n); // positive pow\n\treturn div(1, pow_rec(i, -n)); // negative pow\n};\n\n// 12^7 = 35831808\nconsole.log('12^7 =', pow(I, N));\n\n// 12^7 (2) = 35831808\nconsole.log('12^7 (2) =', pow_opt(I, N));\n\n// 12^7 (3) = 35831808\nconsole.log('12^7 (3) =', pow_opt(I, N, 3));\n\n// 12^7 (4) = 35831808\nconsole.log('12^7 (4) =', pow_opt(I, N, 4));

linkPrime

// Prime factors: https://simple.wikipedia.org/wiki/Prime_factorization\n// Crible primes: https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes\n\nfactors = (n) => {\n\tlet k = 2;\n\tconst primes = [];\n\twhile (k * k <= n) {\n\t\tif (n % k == 0) {\n\t\t\tprimes.push(k);\n\t\t\tn /= k;\n\t\t} else {\n\t\t\tk++;\n\t\t}\n\t}\n\n\tif (n > 1) primes.push(n);\n\n\treturn primes;\n};\n\ncrible = (max, number = 1000000) => {\n\tconst primes = [];\n\n\tif (max >= 2) primes.push(2);\n\n\tfor (let p = 3; p <= max && primes.length < number; p += 2) {\n\t\tlet prime = true;\n\n\t\tfor (let pp of primes) {\n\t\t\tif (p % pp == 0) {\n\t\t\t\tprime = false;\n\t\t\t\tbreak;\n\t\t\t}\n\t\t}\n\n\t\tif (prime) primes.push(p);\n\t}\n\n\treturn primes;\n};\n\n// factors 120 = [ 2, 2, 2, 3, 5 ]\nconsole.log('factors 120 =', factors(120));\n\n// crible 1000 = [ 2, 3, 5, 7, 11, 13, ...]\nconsole.log('crible 1000 =', crible(1000));

","path":"sheets/snippets-analysis","file":"sheets/snippets/analysis"},{"meta":{"title":"Benchmarking","short":"Benchmarking demo with a simple gcd algorithm","topic":"benchmarking"},"html":"

linkBenchmark demo

/*\nJS SIMPLE BENCHMARKING - RUNNING IN WEB JS OR ON NODE SERVER\nTEST WITH A SIMPLE IMPLEMENTATION OF EUCLIDEAN GCD ALGORITHM\n*/\n\nif (typeof window === 'undefined') {\n\tvar { performance } = require('perf_hooks'); // in node\n} else {\n\t// ================ /! Warning /! ================\n\t// reduced time precision (1ms) in Firefox 60\n\t// or with privacy.resistFingerprinting enabled\n\tvar performance = window.performance; // in web browser\n}\n\nconst gcd = (a, b) => (b === 0 ? a : gcd(b, a % b));\n\nconst PASS = 10;\nconst ITER = 10000000;\nconst MAX = 1000000000;\nconst ROUND = 100;\n\nconst passes = [...Array(PASS).keys()].map((i) => {\n\tconst arr = [...Array(ITER).keys()].map(() => Math.floor(Math.random() * (MAX - ROUND)) * ROUND);\n\n\tconst start = performance.now();\n\tconst c_gcd = arr.reduce((acc, val) => gcd(acc, val));\n\tconst end = performance.now();\n\n\tconst time = end - start;\n\tconsole.log(`${i + 1}/${PASS}: gcd = ${c_gcd} (${time}ms)`);\n\n\treturn time;\n});\n\nconst sum = passes.reduce((a, b) => a + b, 0);\n\nconsole.log(`\n==========================================\ntotal duration: ${sum}ms\nmean duration: ${sum / PASS}ms\nmax duration: ${Math.max(...passes)}ms\nmin duration: ${Math.min(...passes)}ms\nmean gcd: ${sum / PASS / ITER}ms\n==========================================\n`);\n\n/*\n============ node v16.15.1 ============\n1/10: gcd = 100 (396.6382689997554ms)\n2/10: gcd = 100 (485.538164999336ms)\n3/10: gcd = 100 (519.4448899999261ms)\n4/10: gcd = 100 (495.69499099999666ms)\n5/10: gcd = 100 (438.1148039996624ms)\n6/10: gcd = 100 (423.10171699896455ms)\n7/10: gcd = 100 (492.2839640006423ms)\n8/10: gcd = 100 (425.25345399975777ms)\n9/10: gcd = 100 (424.4618050009012ms)\n10/10: gcd = 100 (425.43023999780416ms)\n==========================================\ntotal duration: 4525.9622989967465ms\nmean duration: 452.59622989967465ms\nmax duration: 519.4448899999261ms\nmin duration: 396.6382689997554ms\nmean gcd: 0.00004525962298996746ms\n==========================================\n*/

","path":"sheets/snippets-benchmarking","file":"sheets/snippets/benchmarking"},{"meta":{"title":"Charts","short":"Data plotting","topic":"maths visualisation"},"html":"

linkCharts demo

TODO;

","path":"sheets/snippets-charts","file":"sheets/snippets/charts"},{"meta":{"title":"Encoding","short":"Object serialization","topic":"serialization encoding"},"html":"

linkEncoding demo

function encode(o) {\n\tif (Array.isArray(o)) {\n\t\treturn `[${o.map((e) => encode(e)).join(', ')}]`;\n\t} else if (typeof o == 'string') {\n\t\treturn `\"${o}\"`;\n\t} else if (typeof o == 'object') {\n\t\treturn `{ ${Object.entries(o)\n\t\t\t.map(([k, v]) => `${k}: ${encode(v)}`)\n\t\t\t.join(', ')} }`;\n\t} else {\n\t\treturn `${o.toString()}`;\n\t}\n}\n\nconst instance = {\n\ttest: 'a',\n\ttesta: ['a'],\n\tsup: () => {\n\t\tconsole.log('hello from copy');\n\t}\n};\nconsole.log(encode(instance));\n// { test: \"a\", testa: [\"a\"], sup: () => {} }\n\nconst encoded = btoa(escape(encode(instance)));\nconsole.log(encoded);\n// JTdCJTIwdGVzdCUzQSUyMCUyMmElMjIlMkMlMjB0ZXN0YSUzQSUyMCU1QiUyMmElMjIlNUQlMkMlMjBzdXAlM0ElMjAlMjglMjklMjAlM0QlM0UlMjAlN0IlN0QlMjAlN0Q=\n\neval('copy = ' + unescape(atob(encoded)));\nconsole.log(copy);\n// { test: 'a', testa: [ 'a' ], sup: [Function: sup] }\n\ncopy.sup();\n// hello from copy

","path":"sheets/snippets-encoding","file":"sheets/snippets/encoding"},{"meta":{"title":"Functions","short":"Dichotomy, Fixpoint method and Gradients","topic":"maths functions solving"},"html":"

linkDichotomy

// Dichotomic search: https://en.wikipedia.org/wiki/Dichotomic_search\n\ndichotomy = (fn, target, start = 0, end = 10000, delta = 1) => {\n\twhile (start + delta < end) {\n\t\tconst center = (start + end) / 2;\n\t\tif (fn(center) > target) {\n\t\t\tend = center;\n\t\t} else {\n\t\t\tstart = center;\n\t\t}\n\t}\n\n\treturn start;\n};\n\n// log(x) = 6.21516781 <=> x = 500.166015625\nconsole.log('log(x) = 6.21516781 <=> x =', dichotomy(Math.log, 6.21516781, 10, 1000));\n\n// sin(x) = 45 <=> x = 0.7853981633974483\nconsole.log('sin(x) = 45 <=> x =', dichotomy(Math.sin, 45, 0, Math.PI / 2));\n\n// exp(x) = 7.38905609893065 <=> x = 1.9999999995343387\nconsole.log(\n\t'exp(x) = 7.38905609893065 <=> x =',\n\tdichotomy((x) => Math.exp(x), 7.38905609893065, 0, 10, 0.000000001)\n);

linkFixpoint

// Fixpoint : https://en.wikipedia.org/wiki/Fixed-point_iteration\n\nfixpoint = (fn, start, delta) => {\n\tconst MAX_ITER = 10; // max number or iteration before stopping\n\n\titer = (fx, value, delta, c = 0) => {\n\t\tif (c > MAX_ITER)\n\t\t\tthrow `Method doesn't converges with the start at ${start} in the allowed duration (${MAX_ITER} iters)`;\n\n\t\tconst next = fx(value);\n\n\t\tif (Math.abs(value - next) < delta) return value;\n\n\t\treturn iter(fx, next, delta, c + 1);\n\t};\n\n\tfx = (x) => x + fn(x);\n\n\treturn iter(fx, fx(start), delta);\n};\n\n// sin(x) = 0 <=> x = 3.1415926520823465\nconsole.log('sin(x) = 0 <=> x =', fixpoint(Math.sin, 2, 0.0001));\n\n// cos(x) = 0 <=> x = 1.5707963255168476\nconsole.log('cos(x) = 0 <=> x =', fixpoint(Math.cos, -1, 0.0001));

linkGradient

derivative = (fn, x, delta) => (fn(x + delta) - fx(x)) / delta;\n\ntaylor = (fn, x, delta) => (fn(x + delta) - fx(x - delta)) / (2 * delta);

","path":"sheets/snippets-functions","file":"sheets/snippets/functions"},{"meta":{"title":"Graphs","short":"Depth-first search, Breadth-first search, Tortoise and hare","topic":"maths graph-theory"},"html":"

linkDFS

TODO;

linkBFS

TODO;

linkToirtoise and Hare

TODO;

","path":"sheets/snippets-graphs","file":"sheets/snippets/graphs"},{"meta":{"title":"Interpolation","short":"Lagrange polynomial and splines","topic":"maths interpolation"},"html":"

linkLagrange

// https://en.wikipedia.org/wiki/Lagrange_polynomial\n// 1. We have a set of nodes through which the function must pass:  pn = (xn, yn)\n// 2. We obtain the basic equations of the polynomial:              P(xn) = yn\n// 3. We obtain the equations of the polynomial of degree n:        AX^3 + bX^2 + cX + d\n// 4. We replace X by X1, X2, ..., Xn and we obtain a system of equations\n// 5. We solve with one of the methods in the system folder\n//\n// Remark:\n// We know that for n nodes, there exists:\n// - an infinity of polynomials of degree n (or more)\n// - a unique polynomial of (degree n-1 or less)\n\nlagrange = (x, y, X) => {\n\tconst n = x.length;\n\tlet L = 0;\n\n\tfor (let i = 0; i < n; i++) {\n\t\tL += polynom(x, y, i, X);\n\t}\n\n\treturn L;\n};\n\npolynom = (x, y, i, X) => {\n\tconst n = x.length;\n\tLi = 1;\n\n\tfor (let j = 0; j < n; j++) {\n\t\tif (j != i) {\n\t\t\tLi *= X - x[j];\n\t\t}\n\t}\n\n\tfor (let j = 0; j < n; j++) {\n\t\tif (j != i) {\n\t\t\tLi /= x[i] - x[j];\n\t\t}\n\t}\n\n\tLi *= y[i];\n\n\treturn Li;\n};\n\nconst x = [0, 1, 2, 3];\nconst y = [1, 1.1, 1.3, 4];\n\nconsole.log(\n\t'Interpolated function between 0 and 4 =',\n\t[...new Array(40).keys()].map((e) => [e / 10, lagrange(x, y, e / 10)])\n);\n\n/*\nInterpolated function between 0 and 4 = [\n    [0, 1],\n    [0.1, 1.0738999999999999],\n    [0.2, 1.1271999999999998],\n    [0.3, 1.1623],\n    [0.4, 1.1816000000000002],\n    [0.5, 1.1875],\n    [0.6, 1.1824],\n    [0.7, 1.1686999999999999],\n    [0.8, 1.1488000000000003],\n    [0.9, 1.1251000000000004],\n    [1, 1.1],\n    [1.1, 1.0759],\n    [1.2, 1.0552],\n    [1.3, 1.0403000000000002],\n    [1.4, 1.0336],\n    [1.5, 1.0375],\n    [1.6, 1.0544],\n    [1.7, 1.0867],\n    [1.8, 1.1368000000000003],\n    [1.9, 1.2070999999999998],\n    [2, 1.3],\n    [2.1, 1.4179000000000004],\n    [2.2, 1.5632000000000001],\n    [2.3, 1.7382999999999997],\n    [2.4, 1.9455999999999998],\n    [2.5, 2.1875],\n    [2.6, 2.4664],\n    [2.7, 2.7847000000000004],\n    [2.8, 3.144799999999999],\n    [2.9, 3.5490999999999997],\n    [3, 4],\n    [3.1, 4.4999],\n    [3.2, 5.051200000000001],\n    [3.3, 5.656299999999999],\n    [3.4, 6.3176],\n    [3.5, 7.0375],\n    [3.6, 7.818400000000001],\n    [3.7, 8.662700000000001],\n    [3.8, 9.5728],\n    [3.9, 10.5511]\n]\n*/

linkSplines

// https://en.wikipedia.org/wiki/Spline_(mathematics)\n\nTODO;

","path":"sheets/snippets-interpolation","file":"sheets/snippets/interpolation"},{"meta":{"title":"Querying","short":"Data management and querying","topic":"datas querying structures"},"html":"

linkData management and querying

// Simple unsafe hash function\nconst hash1 = (string) => {\n\tlet hash = 0;\n\tfor (let i = 0; i < string.length; i++) {\n\t\tlet char = string.charCodeAt(i);\n\t\thash = (hash << 5) - hash + char;\n\t\thash = hash & hash; // Convert to 32bit integer\n\t}\n\treturn hash;\n};\n\n// Simple really unsafe hash function\nconst hash2 = (string) => {\n\tlet hash = 0;\n\tfor (let i = 0; i < string.length; i++) {\n\t\tlet char = string.charCodeAt(i);\n\t\thash = (1 + hash) * (1 - char);\n\t\thash = hash & hash; // Convert to 32bit integer\n\t}\n\treturn hash;\n};\n\n// Simple really really unsafe hash function\nconst hash3 = (string) => {\n\tlet hash = 0;\n\tfor (let i = 0; i < string.length; i++) {\n\t\tlet char = string.charCodeAt(i);\n\t\thash = hash + char;\n\t\thash = hash & hash; // Convert to 32bit integer\n\t}\n\treturn hash;\n};\n\n// Simple string generator\nconst generator = (\n\tprob_next = 0.8,\n\tmin_length = 15,\n\tmax_length = 30,\n\tchars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'\n) => {\n\tlet generated = '';\n\tfor (let i = 0; i < max_length; i++) {\n\t\tgenerated += chars.charAt(Math.floor(Math.random() * chars.length));\n\t\tif (i > min_length && Math.random() > prob_next) {\n\t\t\treturn generated;\n\t\t}\n\t}\n\treturn generated;\n};\n\nconst headers = ['GENERATED', 'HASHED_1', 'HASHED_2', 'HASHED_3'];\nconst body = [...new Array(10)].map(() => {\n\tconst generated = generator();\n\tconst hashed1 = hash1(generated);\n\tconst hashed2 = hash2(generated);\n\tconst hashed3 = hash3(generated);\n\treturn [generated, hashed1, hashed2, hashed3];\n});\n\nconst table = [headers, ...body].map(([generated, hashed1, hashed2, hashed3]) => {\n\treturn (\n\t\tString(generated).padStart(31) +\n\t\t' | ' +\n\t\tString(hashed1).padStart(15) +\n\t\t' | ' +\n\t\tString(hashed2).padStart(15) +\n\t\t' | ' +\n\t\tString(hashed3).padStart(10)\n\t);\n});\n\n/*\n[\n  '                      GENERATED |        HASHED_1 |        HASHED_2 |   HASHED_3',\n  '            EieujMIpIrPoSEYkEiu |     -1098783833 |        14233498 |       1777',\n  '             0eqLMYR1wnCdJML7vP |      1592119963 |      -328881288 |       1511',\n  '        3IbSEENIkQz9triAzGaBtvr |      -328345915 |      -323498078 |       2065',\n  '              epHGHTDzwOsSpYlXL |      1369545395 |     -1830671313 |       1571',\n  '              C2UHLxVY0fz1YUmFu |     -1566173822 |      1326778804 |       1436',\n  '              gnK9E0ON9t58WlQoU |     -2017585275 |     -1447597194 |       1373',\n  ' j09SZO1onGD4AzqlzTW26AptVMF235 |      1214518969 |      -877031634 |       2409',\n  '            KXCqHvTs6dvqnog8Ixq |       530575551 |      1633577084 |       1803',\n  '             fANepTBm6lmH8IsFDm |        71169439 |      -609237002 |       1551',\n  '        DwqPjD3iSSwNPoakG9ARKVi |      -693201287 |       543544480 |       2009'\n]\n*/\nconsole.log(table);\n\n// https://en.wikipedia.org/wiki/Hash_table\nclass HashTable {\n\tconstructor() {\n\t\t// For demonstration purposes, the size of the hashmap is\n\t\t// way lower than the availlable number of integer indexs\n\t\t// (Number.MAX_SAFE_INTEGER - Number.MIN_SAFE_INTEGER).\n\t\t// => Frequent collisions are to be expected\n\t\tthis.size = 10000;\n\t\tthis.buckets = new Array(this.size).fill(undefined);\n\t\tthis.hash = hash1;\n\t}\n\n\t_HashToIndex(hash) {\n\t\t// this mapping is really bad for most cases, but simple enough for now.\n\t\treturn Math.abs(hash) % this.size;\n\t}\n\n\tset(key, value) {\n\t\tconst hashed = this.hash(key);\n\t\tthis.buckets[this._HashToIndex(hashed)] = value;\n\t}\n\n\tget(key) {\n\t\tconst hashed = this.hash(key);\n\t\treturn this.buckets[this._HashToIndex(hashed)];\n\t}\n\n\thas(key) {\n\t\treturn this.get(key) !== undefined;\n\t}\n}\n\n// https://en.wikipedia.org/wiki/AVL_tree\nclass AVLTree {\n\t// TODO\n}\n\n// https://en.wikipedia.org/wiki/Bloom_filter\nclass BloomFilter {\n\tconstructor() {\n\t\tthis.size = 10000;\n\t\tthis.buckets = new Array(this.size).fill(false);\n\t\tthis.hashes = [hash1, hash2, hash3];\n\t}\n\n\t_HashToIndex(hash) {\n\t\treturn Math.abs(hash) % this.size;\n\t}\n\n\tset(key) {\n\t\tthis.hashes\n\t\t\t.map((hash) => hash(key))\n\t\t\t.forEach((hashed) => {\n\t\t\t\tthis.buckets[this._HashToIndex(hashed)] = true;\n\t\t\t});\n\t}\n\n\thas(key) {\n\t\treturn this.hashes\n\t\t\t.map((hash) => hash(key))\n\t\t\t.map((hashed) => this.buckets[this._HashToIndex(hashed)])\n\t\t\t.reduce((acc, val) => acc && val, true);\n\t}\n}\n\nconst ht = new HashTable();\nconst bf = new BloomFilter();\n\nconst temp = generator(); // zDg6oVTK8dsRZ2HFSAVscri\nht.set(temp, temp);\nconsole.log(ht.has(temp)); // true\nconsole.log(ht.has('aaa')); // false\n\nbf.set(temp);\nconsole.log(bf.has(temp)); // true\nconsole.log(bf.has('aaa')); // false

","path":"sheets/snippets-querying","file":"sheets/snippets/querying"},{"meta":{"title":"Scheduler","short":"Simple scheduler policies demo","topic":"scheduler visualisation"},"html":"

linkScheduler demo

const Status = Object.freeze({\n\tWaiting: -1,\n\tRunning: 0,\n\tTerminated: 1\n});\n\nclass Task {\n\tconstructor(duration, priority = 1) {\n\t\tthis._duration = duration;\n\t\tthis._priority = priority;\n\t\tthis._status = Status.Waiting;\n\t\tthis.trace = '';\n\t}\n\n\tStart() {\n\t\tconst waiting = this._status === Status.Waiting;\n\t\tif (waiting) this._status = Status.Running;\n\t}\n\n\tStop() {\n\t\tconst running = this._status === Status.Running;\n\t\tif (running) this._status = Status.Waiting;\n\t}\n\n\tStep() {\n\t\tconst running = this._status === Status.Running;\n\t\tthis.trace += running ? '█' : ' ';\n\t\tif (running) this._duration--;\n\t\tif (this._duration < 1) this._status = Status.Terminated;\n\t}\n\n\tTerminated() {\n\t\treturn this._status === Status.Terminated;\n\t}\n}\n\nconst Policy = Object.freeze({\n\tFIFO: 'FIFO', // First In First Out\n\tLIFO: 'LIFO', // Last In First Out\n\tSJF: 'SJF', // Shortest Job First\n\tRR: 'RR' // Round Robin\n});\n\n// Preemptive scheduler\nclass Scheduler {\n\tconstructor(tasks, policy, threads = 1) {\n\t\ttasks.forEach((t, i) => (t.id = i));\n\n\t\tthis._policy = policy;\n\t\tthis._threads = threads;\n\t\tthis._queue = [...tasks];\n\t\tthis._pool = [];\n\t\tthis._complete = [];\n\t}\n\n\tSchedule() {\n\t\t// Extract finished tasks\n\t\tfor (let i in this._pool) {\n\t\t\tif (this._pool[i].Terminated()) {\n\t\t\t\tconst task = this._pool.splice(i, 1);\n\t\t\t\tthis._complete.push(...task);\n\t\t\t}\n\t\t}\n\n\t\tswitch (this._policy) {\n\t\t\tcase Policy.FIFO:\n\t\t\t\t{\n\t\t\t\t\t// Insert tasks from the start\n\t\t\t\t\twhile (this._queue.length > 0 && this._pool.length < this._threads) {\n\t\t\t\t\t\tconst task = this._queue.shift();\n\t\t\t\t\t\ttask.Start();\n\t\t\t\t\t\tthis._pool.push(task);\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\tbreak;\n\t\t\tcase Policy.LIFO:\n\t\t\t\t{\n\t\t\t\t\t// Insert tasks from the end\n\t\t\t\t\twhile (this._queue.length > 0 && this._pool.length < this._threads) {\n\t\t\t\t\t\tconst task = this._queue.pop();\n\t\t\t\t\t\ttask.Start();\n\t\t\t\t\t\tthis._pool.push(task);\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\tbreak;\n\t\t\tcase Policy.SJF:\n\t\t\t\t{\n\t\t\t\t\t// Insert tasks from shortest\n\t\t\t\t\twhile (this._queue.length > 0 && this._pool.length < this._threads) {\n\t\t\t\t\t\tconst task = this._queue.sort((a, b) => a._duration - b._duration).shift();\n\t\t\t\t\t\ttask.Start();\n\t\t\t\t\t\tthis._pool.push(task);\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\tbreak;\n\t\t\tcase Policy.RR:\n\t\t\t\t{\n\t\t\t\t\t// Stop running tasks and move them at the end\n\t\t\t\t\tfor (let i in this._pool) {\n\t\t\t\t\t\tconst task = this._pool.shift();\n\t\t\t\t\t\ttask.Stop();\n\t\t\t\t\t\tthis._queue.push(task);\n\t\t\t\t\t}\n\n\t\t\t\t\t// Insert tasks from the start\n\t\t\t\t\twhile (this._queue.length > 0 && this._pool.length < this._threads) {\n\t\t\t\t\t\tconst task = this._queue.shift();\n\t\t\t\t\t\ttask.Start();\n\t\t\t\t\t\tthis._pool.push(task);\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\tbreak;\n\t\t\tdefault:\n\t\t\t\tthrow 'Policy not supported';\n\t\t}\n\t}\n\n\tTrace() {\n\t\twhile (this._queue.length > 0 || this._pool.length > 0) {\n\t\t\tthis.Schedule();\n\n\t\t\tconst every = [...this._queue, ...this._pool, ...this._complete];\n\t\t\tevery.forEach((t) => {\n\t\t\t\tt.Step();\n\t\t\t});\n\t\t}\n\n\t\tconsole.log(`\n________________ ${this._policy} [${this._threads} threads] ________________\n`);\n\n\t\tthis._complete\n\t\t\t.sort((a, b) => a.id - b.id)\n\t\t\t.map((t) => {\n\t\t\t\tconsole.log(`task ${t.id}: ${t.trace}`);\n\t\t\t});\n\t}\n}\n\nconst FIFO = new Scheduler([new Task(10), new Task(5), new Task(10), new Task(7)], Policy.FIFO);\nconst LIFO = new Scheduler([new Task(10), new Task(5), new Task(10), new Task(7)], Policy.LIFO);\nconst SJF = new Scheduler([new Task(10), new Task(5), new Task(10), new Task(7)], Policy.SJF);\nconst RR = new Scheduler([new Task(10), new Task(5), new Task(10), new Task(7)], Policy.RR);\n\nFIFO.Trace();\nLIFO.Trace();\nSJF.Trace();\nRR.Trace();\n\n/*\n________________ FIFO [1 threads] ________________\n\ntask 0: ██████████                       \ntask 1:           █████                  \ntask 2:                ██████████        \ntask 3:                          ███████ \n\n________________ LIFO [1 threads] ________________\n\ntask 0:                       ██████████ \ntask 1:                  █████           \ntask 2:        ██████████                \ntask 3: ███████                          \n\n________________ SJF [1 threads] ________________\n\ntask 0:             ██████████           \ntask 1: █████                            \ntask 2:                       ██████████ \ntask 3:      ███████                     \n\n________________ RR [1 threads] ________________\n\ntask 0: █   █   █   █   █   █  █  █ █ █  \ntask 1:  █   █   █   █   █               \ntask 2:   █   █   █   █   █  █  █  █ █ █ \ntask 3:    █   █   █   █   █  █  █       \n*/

","path":"sheets/snippets-scheduller","file":"sheets/snippets/scheduller"},{"meta":{"title":"Strategies","short":"Bruteforce, Prefixsum and 2-SAT problem","topic":"maths solving"},"html":"

linkBruteforce

// Say we have a problem where we want to test every combination\n// for an array of object, with each object that can be in n states.\n\nconst N = 10; // The number of elements in our array\nconst S = 3; // The number of states in an element\n\n// We know that we will have S^N possible combinations (the nb of\n// array we want to generate).\nconst array = [...Array(Math.pow(S, N)).keys()];\n\n// The best way of doing it (fast, light, clear) is to iterate over\n// a number of N digits in the base of S. The status of the n-th\n// object will be reflected in the value of the n-th digit.\n\nconst combinations = array.map((r) => {\n\tconst based = r.toString(S); // convert to base\n\tconst filler = '0'.repeat(N - based.length); // prepend with 0\n\treturn filler + based; // assert length\n});\n\n// combinations = ['0000000000', '0000000001', '0000000002', '0000000010', '0000000011', ... , '2222222222']\nconsole.log('combinations =', combinations);\n\nconst prepend = (e, ls) => ls.map((sl) => [e, ...sl]);\n\n// prepend = [ [ 1, 2, 3 ], [ 1, 3, 4 ] ]\nconsole.log(\n\t'prepend =',\n\tprepend(1, [\n\t\t[2, 3],\n\t\t[3, 4]\n\t])\n);\n\nconst lists = (ls) => {\n\tif (!ls.length) return [[]];\n\n\tconst [head, ...tail] = ls;\n\tconst sublist = lists(tail);\n\tconst appended = prepend(head, sublist);\n\n\treturn [...sublist, ...appended];\n};\n\n// lists = [[], [3], [2], [2, 3], [1], [1, 3], [1, 2], [1, 2, 3]]\nconsole.log('lists =', lists([1, 2, 3]));\n\nconst inject = (e, ls) => {\n\tif (!ls.length) return [[e]];\n\n\tconst [head, ...tail] = ls;\n\tconst current = [e, ...ls];\n\tconst following = prepend(head, inject(e, tail));\n\n\treturn [current, ...following];\n};\n\n// inject = [ [ 1, 1, 2, 3 ], [ 1, 1, 2, 3 ], [ 1, 2, 1, 3 ], [ 1, 2, 3, 1 ] ]\nconsole.log('inject =', inject(1, [1, 2, 3]));\n\nconst permuts = (ls) => {\n\tif (!ls.length) return [[]];\n\n\tconst [head, ...tail] = ls;\n\n\treturn permuts(tail)\n\t\t.map((sl) => inject(head, sl))\n\t\t.flat();\n};\n\n// permuts = [ [1, 2, 3], [2, 1, 3], [2, 3, 1], [1, 3, 2], [3, 1, 2], [3, 2, 1] ]\nconsole.log('permuts =', permuts([1, 2, 3]));\n\nconst arrangements = (ls) => lists(ls).reduce((acc, sl) => [...acc, ...permuts(sl)]);\n\n// arrangements = [ [3], [ 2 ], [2, 3], [3, 2], [1], [1, 3], [3, 1], [1, 2], [2, 1], [1, 2, 3], [2, 1, 3], [2, 3, 1], [1, 3, 2], [3, 1, 2], [3, 2, 1] ]\nconsole.log('arrangements =', arrangements([1, 2, 3]));\n\nconst partitions = (ls) => {\n\tif (!ls.length) return [];\n\tif (ls.length === 2) return [[[ls[0]], [ls[1]]]];\n\n\tconst [head, ...tail] = ls;\n\n\tconst first = [[head], tail];\n\tconst remain = partitions(tail).map(([ls, rs]) => [[head, ...ls], rs]);\n\n\treturn [first, ...remain];\n};\n\n// partitions = [ [ [ 1 ], [ 2, 3 ] ], [ [ 1, 2 ], [ 3 ] ] ]\nconsole.log('partitions =', partitions([1, 2, 3]));

linkPrefixsum

// Allow to compute the sum of a continuous range in an array of values\n// in o(1) instead of o(n). Require a first step at o(n), so usefull if\n// there is a lot of queries aftewards (and not only one).\n\nconst N = 10000; // number of elements\nconst Q = 1000; // number of queries\n\nconst array = [...Array(N)].map(() => Math.round(Math.random() * 100));\nconst queries = [...Array(Q)].map(() =>\n\t[Math.round(Math.random() * N), Math.round(Math.random() * N)].sort((a, b) => a - b)\n);\n\n// iterative search o(n^2)\nconst iterative = (array, queries) => {\n\tconst results = Array(queries.length).fill(0);\n\n\tfor (let i = 0; i < queries.length; i++) {\n\t\tconst query = queries[i];\n\n\t\tfor (let j = query[0]; j <= query[1]; j++) {\n\t\t\tresults[i] += array[j];\n\t\t}\n\t}\n\n\treturn results;\n};\n\n// prefixed search, o(n)\nconst prefixsum = (array, queries) => {\n\tconst results = Array(queries.length).fill(0);\n\tconst summed = Array(array.length).fill(0);\n\n\tsummed[0] = array[0];\n\tfor (let i = 1; i < summed.length; i++) {\n\t\tsummed[i] = summed[i - 1] + array[i];\n\t}\n\n\tfor (let i = 0; i < queries.length; i++) {\n\t\tconst query = queries[i];\n\n\t\tconst upper = summed[query[1]];\n\t\tconst under = summed[query[0] - 1] ?? 0;\n\t\tresults[i] = upper - under;\n\t}\n\n\treturn results;\n};\n\nconst iter = iterative(array, queries);\nconst pref = prefixsum(array, queries);\n\nconst same = iter.map((_, i) => iter[i] === pref[i]).reduce((acc, cur) => acc && cur);\n\nconsole.log(same);

link2-SAT

// 2-SAT Problem\n// - wikipedia: https://en.wikipedia.org/wiki/2-satisfiability\n// - paper: https://www.sciencedirect.com/science/article/abs/pii/0020019079900024?via%3Dihub\n// - source: https://www.robindar.com/fr/blog/battledev-12-solutions\n// An array of objects, each of which can take two possible values.\n\n// ex: (x1 ∨ x2) ∧ (¬ x1 ∨ x3) ∧ (x2 ∨ x3) ∧ (x4 ∨ ¬ x1), xi ∈ [true, false]\n// => does a combination of xi allow this formula to be true ?\n\n// The 2-SAT formula can be converted to an implication graph\n// (a ∨ b) <=> (¬a ⇒ b ∧ ¬b ⇒ a)\n\n// 1. For each xi, we create a node Vx and V¬x\n// 2. We then add an edge from a to b for each (a ⇒ b)\n// 3. If there is a path from a to b, then a ⇒ b\n// 4. We have to find values for the graph not to contain a (true ⇒ false)\n\n// - (xi → ¬xi) and (¬xi → xi) then no solution\n// - (xi → ¬xi) then xi is false\n// - (¬xi → xi) then xi is true\n// - propagate implications: (a → b) and a is true, then b is true\n\n// To do this, we can decompose the graph in it's \"strongly connected component\"\n// We can do this with the Tarjan algorithm\n\n// Nonogram puzzle solver: https://en.wikipedia.org/wiki/Nonogram\n\n// - https://en.wikipedia.org/wiki/2-satisfiability\n// - https://en.wikipedia.org/wiki/Nonogram

","path":"sheets/snippets-strategies","file":"sheets/snippets/strategies"},{"meta":{"title":"System","short":"Gaussian elimination, Jacobi method and Gauss-Siedel","topic":"maths system solving"},"html":"

linkGaussian

// https://en.wikipedia.org/wiki/Gaussian_elimination\n// Gauss elimination (Direct method)\n// 1. Triangulation of the square matrix A with b\n// 2. Backward substitution to obtain the values of x\n\ngauss = (A, b) => {\n\t[A, b] = triangulation(A, b);\n\treturn subsitution(A, b);\n};\n\n// Transformation into a superior triangular matrix\ntriangulation = (A, b) => {\n\tconst n = A.length;\n\tfor (let k = 0; k < n - 1; k++) {\n\t\tif (Math.abs(A[k][k]) < 0.00001) {\n\t\t\tthrow 'Triangulation is not possible with this matrix';\n\t\t}\n\n\t\tfor (let i = k + 1; i < n; i++) {\n\t\t\tconst m = A[i][k] / A[k][k];\n\t\t\tb[i] = b[i] - m * b[k];\n\t\t\tA[i][k] = 0;\n\n\t\t\tfor (let j = k + 1; j < n; j++) {\n\t\t\t\tA[i][j] -= m * A[k][j];\n\t\t\t}\n\t\t}\n\t}\n\n\treturn [A, b];\n};\n\n// Retrograde substitution\nsubsitution = (A, b) => {\n\tconst n = A.length;\n\tlet x = new Array(n).fill(0);\n\n\tfor (let i = 0; i < n; i++) {\n\t\tconst j = n - i - 1;\n\t\tx[j] = b[j];\n\t\tfor (let k = j + 1; k < n; k++) {\n\t\t\tx[j] -= A[j][k] * x[k];\n\t\t}\n\t\tx[j] /= A[j][j];\n\t}\n\n\treturn x;\n};\n\nconst A = [\n\t[1, 1, 1],\n\t[1, 0.4, 0],\n\t[10, 5, 1]\n];\n\nconst b = [24, 14, 152];\n\n// [ 11.999999999999993, 5.000000000000013, 6.999999999999992 ]\nconsole.log(gauss(A, b));\n\n/*\nA = [\n    [ 1, 1, 1 ],\n    [ 0, -0.6, -1 ],\n    [ 0, 0, -0.6... ]\n] \n\nb = [ 24, -10, -4.6... ]\n\nx = [ 12.0, 5.0, 7.0 ]\n*/

linkJacobi

// https://en.wikipedia.org/wiki/Jacobi_method\n// Jacobi method (Iterative method)\n// We know that the method works if the diagonal of the matrix A is strictly dominant\n// => Don't hesitate to tweak the matrix to reach this configuration\n\njacobi = (A, b, x0, epsilon) => {\n\tlet diff = epsilon + 1;\n\tlet x = x0; // initial value\n\n\twhile (diff > epsilon) {\n\t\tconst temp_x = x;\n\t\tx = iter(A, b, x);\n\n\t\tdiff_x_temp = x.map((_, i) => x[i] - temp_x[i]);\n\n\t\t// https://en.wikipedia.org/wiki/Uniform_norm\n\t\tdiff = Math.max(...diff_x_temp.map(Math.abs));\n\t}\n\n\treturn x;\n};\n\niter = (A, b, x) => {\n\tconst n = A.length;\n\tlet x1 = [...x]; // copy values\n\n\tfor (let i = 0; i < n; i++) {\n\t\tx1[i] = b[i];\n\t\tfor (let j = 0; j < n; j++) {\n\t\t\tif (j != i) {\n\t\t\t\tx1[i] -= A[i][j] * x[j];\n\t\t\t}\n\t\t}\n\t\tx1[i] /= A[i][i];\n\t}\n\n\treturn x1;\n};\n\n// With strictly doinant diagonal\nconst A = [\n\t[4, -1, 0],\n\t[-1, 4, -1],\n\t[0, -1, 4]\n];\n\nconst b = [6, 4, 6];\n\n// [ 1.999969482421875, 1.999969482421875, 1.999969482421875 ]\nconsole.log(jacobi(A, b, [1, 1, 1], 0.0001));\n\n/*\nA = [\n    [4, -1, 0],\n    [-1, 4, -1],\n    [0, -1, 4]\n] \n\nb = [6, 4, 6]\n\nx = [ 2, 2, 2 ]\n*/

linkSiedel

// https://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method\n//We know that the Gauss-Seidel method converges twice as fast as the Jacobi method\n// if the matrix A is strictly dominant diagonal\n\nsiedel = (A, b, x0, epsilon) => {\n\tlet diff = epsilon + 1;\n\tlet x = x0; // initial value\n\n\twhile (diff > epsilon) {\n\t\tconst temp_x = x;\n\t\tx = iter(A, b, x);\n\n\t\tdiff_x_temp = x.map((_, i) => x[i] - temp_x[i]);\n\n\t\t// https://en.wikipedia.org/wiki/Uniform_norm\n\t\tdiff = Math.max(...diff_x_temp.map(Math.abs));\n\t}\n\n\treturn x;\n};\n\niter = (A, b, x) => {\n\tconst n = A.length;\n\tlet x1 = [...x]; // copy values\n\n\tfor (let i = 0; i < n; i++) {\n\t\tx1[i] = b[i];\n\t\tfor (let j = 0; j < n; j++) {\n\t\t\tif (j > i) {\n\t\t\t\tx1[i] -= A[i][j] * x[j];\n\t\t\t} else if (j < i) {\n\t\t\t\tx1[i] -= A[i][j] * x1[j];\n\t\t\t}\n\t\t}\n\t\tx1[i] /= A[i][i];\n\t}\n\n\treturn x1;\n};\n\n// With strictly doinant diagonal\nconst A = [\n\t[1, 1, 1],\n\t[1, 0.4, 0],\n\t[10, 5, 1]\n];\n\nconst b = [24, 14, 152];\n\n// [ 12, 5, 7 ]\nconsole.log(siedel(A, b, [1, 1, 1], 0.0001));\n\n/*\nA = [\n    [1, 1, 1],\n    [1, 0.4, 0],\n    [10, 5, 1]\n]\n\nb = [24, 14, 152]\n\nx = [ 12, 5, 7 ]\n*/

","path":"sheets/snippets-systems","file":"sheets/snippets/systems"}]

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