To get started with writing C++, open the Vscode and write your first "Hello world" c++ code:

• #include <'iostream>
• int main()
• {
• std::cout << "Hello, World!" << std::endl;
• return 0;
• }

In C++, a variable is a named location in memory that is used to store a value. When you declare a variable, you specify its type and name, and you can then use the variable to store and manipulate data in your program.

There are several ways to declare variables in C++. The most basic way is to simply specify the data type and the name of the variable:

With the keyword int. For example,

• int x = 42.

Once a variable is declared, you can use it to store and manipulate data in your program. For example, you can assign a new value to the variable, or you can use it in an expression:

• x = 30; // Assign a new value to the variable "x"
• int newX = x + 5; // Use the variable "x" in an expression to calculate a new value

In C++, the scope of a variable refers to the region of the program in which the variable is visible or can be accessed. A variable's scope determines where it can be used in the program and how long it will exist in memory.

There are two main types of variable scope in C++: local scope and global scope.

a global variable is a variable that is defined outside of any block of code, such as a function or loop, and is therefore visible and accessible throughout the entire program. Global variables are created when the program starts and are destroyed when the program ends.

Global variables are useful in situations where you need to share data between different parts of your program, such as between functions or across multiple source files. However, they can also introduce complexity and can make it more difficult to understand the behavior of your code, especially if they are used extensively.

A constant is a value that cannot be modified once it has been set. Constants are often used to define values that are used frequently throughout a program and that should not be changed by accident.

There are several ways to define constants in C++. One way is to use the "const" keyword to define a constant variable:

• const int MAX_ITEMS = 100; // Define a constant called "MAX_ITEMS" with the value 100

Another way to define constants in C++ is to use the "define" directive:

• #define MAX_ITEMS 100 // Define a constant called "MAX_ITEMS" with the value 100

It's important to use constants to define values that should not be changed, as it helps to make your code more maintainable and less prone to errors. Constants also make your code more readable, as they provide a meaningful name for the value rather than just using a hard-coded number.

there are several different data types that you can use to declare variables. The most basic data types are the built-in types, which include:

• Integer types: "int", "short", "long", and "long long"
• Floating-point types: "float", "double", and "long double"
• Boolean type: "bool"
• Character type: "char"

In addition to the built-in types, C++ also allows you to define your own custom data types using user-defined types, such as "struct" (structure) and "class" (class). These types allow you to create complex data structures and objects that can represent real-world entities in your program.

In C++, the "if-else" statement is a control flow statement that allows you to execute a block of code conditionally based on the value of a Boolean expression. The Boolean expression is evaluated, and if it is found to be true, the code in the "if" block is executed. If the Boolean expression is false, the code in the "else" block is executed instead.

• if (condition) { statement_1; } else { statement_2; }

You may also compound the statements using else if to have multiple conditions tested in sequence, as follows:

• if (condition_1) { statement_1; } else if (condition_2) {
• statement_2; } else if (condition_n) { statement_n; } else {
• statement_last; }

In the case of multiple conditions only the first logical condition which evaluates to true will be executed. To execute multiple statements, group them within a block statement ({ ... }) . In general, it's good practice to always use block statements, especially when nesting if statements:

• if (condition) { statement_1_runs_if_condition_is_true;
• statement_2_runs_if_condition_is_true; } else {
• statement_3_runs_if_condition_is_false;
• statement_4_runs_if_condition_is_false; }

the "while" statement is a control flow statement that allows you to execute a block of code repeatedly as long as a given condition is true. The "while" statement continuously evaluates a Boolean expression and, if the expression is found to be true, it executes the code in the loop body. The loop continues to execute until the Boolean expression is false.

• while (condition) statement

The "while" loop is a useful tool for executing a block of code repeatedly, and it is often used when you don't know in advance how many times the loop will need to execute. It is important to ensure that the Boolean expression used in the "while" loop eventually becomes false, or the loop will execute indefinitely and your program will become stuck in an infinite loop.

A function definition (also called a function declaration, or function statement) consists of the function keyword, followed by:

• The name of the function.
• A list of arguments to the function, enclosed in parentheses and separated by commas.
• The C++ statements that define the function, enclosed in curly brackets, { }.

For example, the following code defines a simple function named add:

• int add(int x, int y) {
• return x + y; // Return the sum of "x" and "y"
• }

• All the documentation in this page is taken from MDN