C++ is a popular programming language
C++ is used to create computer programs, and is one of the most used language in game development.
Examples in Each Chapter
Our “Try it Yourself” editor makes it easy to learn C++. You can edit C++ code and view the result in your browser.
Example
#include <iostream>
using namespace std;
int main() {
cout << “Hello World!”;
return 0;
Click on the “Run example” button to see how it works.
We recommend reading this tutorial, in the sequence listed in the left menu.
C++ is an object oriented language and some concepts may be new. Take breaks when needed, and go over the examples as many times as needed.
C++ Exercises
Test Yourself With Exercises
Exercise:
Insert the missing part of the code below to output “Hello World”.
int main() {
<< "Hello World!";
return 0;
}
What exactly is C++?
C++ is a cross-platform programming language for developing high-performance applications.
Bjarne Stroustrup created C++ as an extension to the C programming language.
C++ gives programmers a lot of power over the system’s memory and resources.
C++11, C++14, and C++17 were the three main updates to the language in 2011, 2014, and 2017.
Why Should You Use C++?
C++ is one of the most widely used programming languages in the world.
Today’s operating systems, graphical user interfaces, and embedded systems all use C++.
C++ is an object-oriented programming language that offers programs a clear structure and permits code reuse, which reduces development costs.
C++ is a portable programming language that may be used to create applications that run on a variety of systems.
C++ Get Started
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 (see below).
C++ Install 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.
Note: Web-based IDE’s can work as well, but functionality is limited.
We will use Code::Blocks in our tutorial, which we believe is a good place to start.
You can find the latest version of Codeblocks at http://www.codeblocks.org/downloads/26. Download the mingw-setup.exe file, which will install the text editor with a compiler.
C++ Quickstart
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):
myfirstprogram.cpp
#include <iostream>
using namespace std;
int main() {
cout << “Hello World!”;
return 0;
}
Don’t worry if you don’t understand the code above – we will discuss it in detail in later chapters. For now, focus on how to run the code.
In Codeblocks, it should look like this:
C++ Syntax
Let’s break up the following code to understand it better:
Example
#include <iostream>
using namespace std;
int main() {
cout << “Hello World!”;
return 0;
}
Example explained
Line 1: #include <iostream> is a header file library that lets us work with input and output objects, such as cout (used in line 5). Header files add functionality to C++ programs.
Line 2: using namespace std means that we can use names for objects and variables from the standard library.
Don’t worry if you don’t understand how #include <iostream> and using namespace std works. Just think of it as something that (almost) always appears in your program.
Line 3: A blank line. C++ ignores white space. But we use it to make the code more readable.
Line 4: Another thing that always appear in a C++ program, is int main(). This is called a function. Any code inside its curly brackets {} will be executed.
Line 5: cout (pronounced “see-out”) is an object used together with the insertion operator (<<) to output/print text. In our example it will output “Hello World”.
Note: Every C++ statement ends with a semicolon ;.
Note: The body of int main() could also been written as:int main () { cout << "Hello World! "; return 0; }
Remember: The compiler ignores white spaces. However, multiple lines makes the code more readable.
Line 6: return 0 ends the main function.
Line 7: Do not forget to add the closing curly bracket } to actually end the main function.
Omitting Namespace
You might see some C++ programs that runs without the standard namespace library. The using namespace std line can be omitted and replaced with the std keyword, followed by the :: operator for some objects:
Example
#include <iostream>
int main() {
std::cout << “Hello World!”;
return 0;
}
C++ Output (Print Text)
The cout object, together with the << operator, is used to output values/print text:
Example
#include <iostream>
using namespace std;
int main() {
cout << “Hello World!”;
return 0;
}
You can add as many cout objects as you want. However, note that it does not insert a new line at the end of the output:
Example
#include <iostream>
using namespace std;
int main() {
cout << “Hello World!”;
cout << “I am learning C++”;
return 0;
}
New Lines
To insert a new line, you can use the \n character:
Example
#include <iostream>
using namespace std;
int main() {
cout << “Hello World! \n“;
cout << “I am learning C++”;
return 0;
}
Tip: Two \n characters after each other will create a blank line:
Example
#include <iostream>
using namespace std;
int main() {
cout << “Hello World! \n\n“;
cout << “I am learning C++”;
return 0;
}
Another way to insert a new line, is with the endl manipulator:
Example
#include <iostream>
using namespace std;
int main() {
cout << “Hello World!” << endl;
cout << “I am learning C++”;
return 0;
}
Both \n and endl are used to break lines. However, \n is used more often and is the preferred way.
C++ 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
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:
Example
// This is a comment
cout << “Hello World!”;
This example uses a single-line comment at the end of a line of code:
Example
cout << “Hello World!”; // This is a comment
C++ Multi-line Comments
Multi-line comments start with /* and ends with */.
Any text between /* and */ will be ignored by the compiler:
Example
/* The code below will print the words Hello World!
to the screen, and it is amazing */
cout << “Hello World!”;
Single or multi-line comments?
It is up to you which you want to use. Normally, we use // for short comments, and /* */ for longer.
C++ 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 -123double– stores floating point numbers, with decimals, such as 19.99 or -19.99char– stores single characters, such as ‘a’ or ‘B’. Char values are surrounded by single quotesstring– stores text, such as “Hello World”. String values are surrounded by double quotesbool– stores values with two states: true or false
Declaring (Creating) Variables
To create a variable, specify the type and assign it a value:
Syntax
typevariableName = value;
Where type is one of C++ types (such as int), and variableName 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:
Example
Create a variable called myNum of type int and assign it the value 15:int myNum = 15;
cout << myNum;
You can also declare a variable without assigning the value, and assign the value later:
Example
int myNum;
myNum = 15;
cout << myNum;
Note that if you assign a new value to an existing variable, it will overwrite the previous value:
Example
int myNum = 15; // myNum is 15
myNum = 10; // Now myNum is 10
cout << myNum; // Outputs 10
Other Types
A demonstration of other data types:
Example
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)
You will learn more about the individual types in the Data Types chapter.
Display Variables
The cout object is used together with the << operator to display variables.
To combine both text and a variable, separate them with the << operator:
Example
int myAge = 35;
cout << “I am ” << myAge << ” years old.”;
Add Variables Together
To add a variable to another variable, you can use the + operator:
Example
int x = 5;
int y = 6;
int sum = x + y;
cout << sum;
C++ Exercises
Test Yourself With Exercises
Exercise:
Create a variable named myNum and assign the value 50 to it.
C++ User Input
You have already learned that cout is used to output (print) values. Now we will use cin to get user input.
cin is a predefined variable that reads data from the keyboard with the extraction operator (>>).
In the following example, the user can input a number, which is stored in the variable x. Then we print the value of x:
Example
int x;
cout << “Type a number: “; // Type a number and press enter
cin >> x; // Get user input from the keyboard
cout << “Your number is: ” << x; // Display the input value
Good To Know
cout is pronounced “see-out”. Used for output, and uses the insertion operator (<<)
cin is pronounced “see-in”. Used for input, and uses the extraction operator (>>)
Creating a Simple Calculator
In this example, the user must input two numbers. Then we print the sum by calculating (adding) the two numbers:
Example
int x, y;
int sum;
cout << “Type a number: “;
cin >> x;
cout << “Type another number: “;
cin >> y;
sum = x + y;
cout << “Sum is: ” << sum;