---
title: C++
---
# Hello World! - Your First C++ Program

## What is C++?

* C++ is a general purpose programming language which has been used since the 1990's
* It was designed by Bjarne Stroustrup under the name "C with classes".
* It is a version of C that includes Object-Oriented elements, including classes and functions.

* It is considered one of the biggest programming languages, as you can see in the following image:
![Img](http://static1.businessinsider.com/image/59deb30392406c21008b6148-1200/for-bonus-points-heres-the-chart-showing-these-languages-relative-popularity.jpg)
_source: Github_

### Your First Program in C++

```cpp
#include <iostream>
using namespace std;
int main()
{
    cout << "Hello World" << endl;
    return 0;
}
```

#### The Output of this program will be:

```
Hello World!
```

Now, let's break down the code:


#### Lines 1 and 2

```cpp
#include <iostream>
using namespace std;
```

* The first line tells the computer to use the "iostream" header file for this specific program. A header file is a separate file with prewritten C++ code. There are many other header files which are required for a specific program to run properly. For example, math, vector, string, etc. Header files are generally represented by a ".h" extension, when including standard library header files you don't include the ".h" extension.
* The `iostream` header contains the public interface for the input-output stream from the standard library. The "iostream" file contains code for allowing the computer to take input and generate an output, using the C++ language.
* The second line tells the computer to use the standard namespace which includes features of standard C++. You could write this program without this line, but you'd have to use `std::cout` instead of `cout` and `std::endl` instead of `endl` on line 4. It makes the code more readable and our lives as programmers easier.

#### Line 3 and 4

```cpp
int main()
{
```

* C++ starts execution of a program from the -main function- `int main()` . During execution, the computer starts running the code from every line from `{`(opening bracket) till `}`(closing bracket)
  **NOTE : Every function starts with an opening curly brace "{" and ends with a closing curly brace "}".**
* Line 4 indicates the start of the main() function. 

#### Lines 5, 6 & 7

```cpp
    cout << "Hello World" << endl;
    return 0;
}
```

* The word `cout` in C++ is used to stream data to standard output. 
* It is followed by `<<` , the _insertion operator_. 
* Whatever is in the double quotes `""` is printed. Certain special characters have a different syntax for print statements   
* Now to print any other kind of data, you have to  add `<<`.

***Challenge: Change Hello World to another sentence. What will be the output?***

* `endl` is another symbol from the iostream library which means to **end this line and go to the next line during output** .   - _cout stands for "console output"_
* Finally, finish the statement with a semicolon `;`.

**NOTE : Every statement except the main function definition and the #include directive needs to be ended by the semicolon. Without a ";", you may encounter a compiler error.**

* `return 0;` safely terminates the current function i.e. 'main()' in this case and since no function follows after 'main()' the program is terminated. 
* Don't forget to tell the computer that this is end of the main() function. To do this , you add the closing curly brace "}". You will encounter compiler error before program execution if you do not include the **}** .

### The code should look something like this:

![Img](https://i.imgur.com/d1liGwI.png)

Programmers use a Hello World program (like this one) as a ritual on using a new programming language. It is a symbol of good luck.  
_You have finished coding your first C++ program and have understood most of the code you have written/typed. CONGRATULATIONS!_
 
 **Good Luck to all of you and happy coding! :)**
 
 **Happy Coding ! :)**
 
 **Feel free to ask any questions on FreeCodeCamp's GitHub page or [FreeCodeCamp's Forum.](https://forum.freecodecamp.org/)**

 [Try it yourself ! :)](https://repl.it/L4k3)

**You need software to write and execute C++ code, download from one of the links below:**

[Codeblocks](http://www.codeblocks.org/downloads/26)  
[Xcode](https://developer.apple.com/xcode/)  
[Eclipse](http://www.eclipse.org/downloads/)