Introduction

C++ is one of the world's most popular programming languages.
C++ can be found in today's operating systems, Graphical User Interfaces, and embedded systems.
C++ is an object-oriented programming language which gives a clear structure to programs and allows code to be reused, lowering development costs.
C++ is portable and can be used to develop applications that can be adapted to multiple platforms.

Hello World

To start using C++, you need two things:

A text editor, like Notepad, to write C++ code
A compiler, like GCC, to translate the C++ code into a language that the computer will understand

There are many text editors and compilers to choose from. In this tutorial, we will use an IDE . An IDE (Integrated Development Environment) is used to edit AND compile the code.
Popular IDE's include Code::Blocks, Eclipse, and Visual Studio. These are all free, and they can be used to both edit and debug C++ code.
We will use Code::Blocks in our tutorial, which we believe is a good place to start.
Let's create our first C++ file. Open Codeblocks and go to File > New > Empty File. Write the following C++ code and save the file as myfirstprogram.cpp (File > Save File as):


        #include <iostream>
        

        using namespace std;
        

        int main()
        

        {
        

        cout << "Hello World!" ; 

        return 0;
        

        }

Comments

Comments can be used to explain C++ code, and to make it more readable. It can also be used to prevent execution when testing alternative code. Comments can be singled-lined or multi-lined.
Single-line comments start with two forward slashes (//).
Any text between // and the end of the line is ignored by the compiler (will not be executed).
This example uses a single-line comment before a line of code:


         // This is a comment
        

        cout << "Hello World!" ;

This example uses a single-line comment at the end of a line of code:


        cout << "Hello World!" ;
        // This is a comment

Multi-line comments start with /* and ends with */.
Any text between /* and */ will be ignored by the compiler:


        
          /* The code below will print the words Hello World! to the screen, and
          it is amazing */
        

        cout << "Hello World!" ;

Variables

Variables are containers for storing data values.
In C++, there are different types of variables (defined with different keywords), for example:

int - stores integers (whole numbers), without decimals, such as 123 or -123
double - stores floating point numbers, with decimals, such as 19.99 or -19.99
char - stores single characters, such as 'a' or 'B'. Char values are surrounded by single quotes
string - stores text, such as "Hello World". String values are surrounded by double quotes
bool - stores values with two states: true or false

Declaring (Creating) Variables

To create a variable, you must specify the type and assign it a value:

type variable = value;

Where type is one of C++ types (such as int), and variable is the name of the variable (such as x or myName). The equal sign is used to assign values to the variable.
To create a variable that should store a number, look at the following example:

int myNum = 15;

        cout << myNum;

You can also declare a variable without assigning the value, and assign the value later:

int myNum;

        myNum = 15;

        cout << myNum;

Note that if you assign a new value to an existing variable, it will overwrite the previous value:


        int myNum = 15;
        // myNum is 15

        myNum = 10; // Now myNum is 10

        cout << myNum; // Outputs 10

Other Types

A demonstration of other data types:

int myNum = 5;
        // Integer (whole number without decimals)

        double myFloatNum = 5.99;
        // Floating point number (with decimals)

        char myLetter = 'D';
        // Character

        string myText = "Hello";
        // String (text)

        bool myBoolean = true;
        // Boolean (true or false)

Reference

All the information in this page is taken from the w-3 schools c++ tutorial