Written by 4zv4l
on October 17, 2022

Basic Coding

A mini document that I had made to quickly explain the basics of programming.

translated quickly and dirty with Google translate

What’s the point ?

Programming automates a task that a computer/machine can perform. To do this it is necessary to translate an algorithm into a language that the computer can understand (binary).

The variables

Variable types

Here is a short example of a program in pseudo-code (fictional language):

print("What's your name?"); // displays What is your name?
string name = input(); // read what the user writes
print(name); // displays its name


print("How old are you?");
int age = input();
print(age);

In this pseudo-code I used 2 different types of variable:

int: Integer: Number
string: Character string

There are mainly 5 of them:

Type	Name	Example
`char`	Character	‘it’
`bool`	Boolean	true
`int`	Integer	35
`float`	Floating number	3.14
`string`	Character string	“Bonjour Monde !”

Declare a variable

Declaring a variable allows you to say OK! I’m going to need this variable, I’m not putting a value in it at the moment but I’m going to need it.

To declare a variable in pseudo-code:

type name;

example:

string city;

declare city as a variable of type string

Assign variable

Assigning a variable means, assigning it a value.

Assignment is done using the = sign.

example:

string city;
city = "Brussels";

To declare AND to affect a variable at once it is necessary

type name = value;

For example

string city = "Brussels";

Functions

A function makes it possible to associate a piece of code with a name, which can make it possible to reuse it without being redundant.

example:

int requestAge() {
     print("How old are you?");
     int age = input();
     return age;
}

In this example the name of the function is requestAge, it could have been called request_age also (or whatever name you prefer).

It is possible to give arguments to a function.

Here is an example:

int readNumber(phrase) {
     print(sentence)
     int number = input()
     return number;
}

int main() {
     int age = readNumber("What is your name?");
     int zip_code = readNumber("What is your zip code?");
}

The readNumber function displays a sentence to the user and then reads a number, returns the number to the calling function (here main calls readNumber), which allows it to be reused for two similar but different uses. And saves a few redundant lines of code.

The scope of variables

The scope of a variable or in other words lifetime defines the place in the code where you can use the variable.

example

int main() {
     int x = 5;
     {
         int y = 4;
     }
     x=2;
}

this example is valid, x is contained between the 2 larger braces, as for y in the 2 smaller braces.

bad example:

int main() {
     int x = 5;
     {
         int y = 4;
     }
     x=2;
     y=2; // won't work
}

here, we try to use y while the variable is not defined in this scope.
// are comments, the code that follows // does not count, it makes it possible to comment code and understand it more easily later.

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