C++ Tutorial For Beginners

C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It's one of the most popular programming languages and it is widely used in the software industry.


1.0 Preparation

The first step is to get a good IDE (Integrated Development Environment). To be totally honest, you don't really have to get an IDE, but this tutorial will not cover other solutions (yet).

1.1 Windows

If you are a university student you probably have, or can get, an msdnaa account. There you can download Microsoft Visual Studio Professional (VS). Do so.

If you don't have, and can't get, an msdnaa acount, you could use the express edition. It's free. If you really want the professional one, torrent it. If you don't want to torrent it, buy it. If you don't want to buy it either, get one of the following:

Now install whatever you got. Please note that for (at least) Eclipse you'll need a C++ compiler, like g++, included in mingw. You'll also need to properly configure your Path. We won't go into much detail since it's very well documented online.

1.2 Linux

2.0 Hello World

Create a new cpp file and write the following:

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

Compile and run it.

Add the following line, just before return 0; if you can't see the results:


This line will make the program wait for you to press RETURN. Never replace the above line with system("PAUSE");. A lot of books tell you to do this, but it is bad. Very bad. It's not portable (PAUSE isn't there on *nix) and it's not efficient (your program is halted to let it call a command on your intepreter).

2.1 Explanation of the Hello World Example

To get a basic understanding of the Hello World program, you will only need to read the first sentence(s) in each paragraph below.

The first line tells the compiler to insert the iostream header into the file being compiled. This particular header provides basic input and output (IO) functionality.

The second line tells the compiler to look for functions in the namespace called std. A statement like this allows you to use the functions declared in that namespace, in the block or cope in which it was stated. The entire C++ standard library is declared within the std namespace.

In the third line we declare a function called main that returns an int (integer). The main function is a special function in C++. The compiler looks for this function and executes it first, even if we have a lot of other functions in our program. It should always return an int. This is important. Do not listen to anyone telling you to write void main() instead of int main(), just to make the code shorter. Google it to get a more in-depth explanation of why this is bad.

The last character on the third line starts a new block. The block is everything between { and } . These are called curly brackets or braces. Between these we define the main function, e.g. we tell the main function what to do.

The fourth line will usually print Hello World on your console/terminal. This is the first thing our main function will do. cout is the standard output stream. << is the operator used to send data to the stream. "Hello World" represents the string Hello World. A string is a sequence of characters. In the fourth line we send the string Hello World to the standard output stream, cout. Next, we manipulate the stream using endl. endl inserts a newline character and flushes the buffer, if used on a buffered stream.

The fifth line returns an int, and the main function exits.

In the sixth line we close the the block that we opened on the third line. This means the definition of the main function is finished.


Comments are used to explain code, and can work as documentation. It's very easy to comment and it is also very important. The compiler will ignore comments and does not try to understand them. A comment can look like this:

// Print Hello World! on the console.
cout << "Hello World!" << endl;

Above we explained what we were going to do. This can help other programmers to understand our code.

A comment can also look like this:

/* Print Hello World! on the console. */
cout << "Hello World!" << endl;

You may be asking yourself why you would need two ways to do the same thing. Well, the truth is, they are not the same thing. When using //, the comment will only last for the remainder of the line. That means that this will not work:

//Print Hello World!
on the console.
cout << "Hello World!" << endl;

and this will:

cout << "Hello World!" << endl; //Print Hello World! on the console.

If we want to write a longer comment it's appropriate to use /* and */. Then, the comment will begin when we write /* and will end when we write */.

cout << "Hello World" << endl; 

4.0 Variables And Primitive Data Types

4.1 Declaration And Initialization Of Variables

As before, we start this section with an example.

int a;

Above, we declared a variable named a that can hold an int value. Variable declarations are always of the form: type name.

The variable a above has yet to be assigned a value. We can do this by writing:

a = 10;

The value 10 is now stored in the variable a. This is called an assignment. If this is the first time we assign a value to a we can also call this operation an initialization. However, for this to work, the variable a must have been declared before.

If we wish to declare and initialize a variable in a single statement we can do it like this:

int a = 10;

4.2 Using Variables

We can now use this variable in other operations. We may wish to declare a new variable and initialize it with the same value as a.

int b = a;

We may also wish to perform different operations depending on the variables type. One way to use int variables is to perform additions.

int a = 10;
int b = a + 1;

Above we initialized the variable b with a + 1 which is 11. We can even do something like this:

int a = 10;
int b = 10;
b = a + 1;
int c = b + a;

The value stored in b has changed from being 10 to being 11. The value stored in c is 21.

Other operation between numeric types can look like this:

a - b
a * b
a / b
a % b //modulus Gets remainder of a division

When performing assignments it's important to understand the order in which things happen. We will look at the following example and explain:

int c = b + a;

First, the expression b + a is evaluated. Then we assign this value to a newly created variable c.

Knowing this we can easily understand the following:

int d = 0;
d = d + 1;

What might the value stored in d be? First we have to evaluate d + 1. This turns out to be 1. Then, the value 1 is assigned to d.

A short way to do this is by using the += operator. Like this:

int d = 0;
d += 1;

The += operator is called a compound-assignment operator. We can perform all arithmetic operations this way. Here are some examples:

int d = 0;
d += 2;
d -= 3;
d *= 4;
d /= 5;

In C++, and in a lot of other programming languages, there is a shorthand for changing the value stored in an integer variable with only 1.

int d = 0;
d++; // suffix, increment
d--; // suffix, decrement

It's important to note that d++ will only add 1 to the value stored in d. I we want to add anything else we will have to use one of the other methods used above and replace 1 with something else.

We now know 2 different ways of changing and int with 1. But that's not the end of the story. We can also do the following:

int d = 0;
++d; // prefix, increment
--d; // prefix, decrement

But how do they differ? The difference may seem subtle but it's important to understand. And we can do just that by looking at the following example:

int d = 0;
int e = d++;
int f = ++d;

If you have never programmed before you may think that e is storing the value 1 and f is storing the value 2. However, one of those assertions are false. When using the suffix increment, the value passed to e is the initial value of d, which is 0. The value store in d is still incremented by 1. When using the prefix increment, the returned value is the new value of d, which is 2.

4.3 Primitive Data Types In C++

Name        Description              Size*                          Range*

char        Character                1byte       signed          -128 to 127 
												 unsigned           0 to 255 
short int   Integer.                 2bytes      signed        -32768 to 32767 
												 unsigned           0 to 65535 
int         Integer.                 4bytes      signed   -2147483648 to 2147483647 
												 unsigned           0 to 4294967295
long int    Long integer.            4bytes      signed   -2147483648 to 2147483647 
												 unsigned           0 to 4294967295
bool        Boolean value.           1byte       true or false      0 to 1

float       Floating point number    4bytes  ± 3.4e ± 38     ~7 digits

double      Double precision         8bytes  ± 1.7e ± 308    ~15 digits
			floating point number.

long double Long double precision    8bytes  ± 1.7e ± 308    ~15 digits
			floating point number.        

wchar_t     Wide character.        2/4bytes                  1 wide character

* Size and range are system dependant. The values shown above are those found on most 32-bit systems.

5.0 Conditional Statements And Boolean Expressions

What happens if we want some code to execute only when a specific condition is true or false? We use a conditional statement of course.

5.1 If Statements

An if statement allows you to control if a program enters a section of code or not based on whether a given condition is true or false. Here is an example:

if (1 < 10) {
	cout << "Hello" << endl;

Since 1 is less than 10, the string Hello is printed on the console. This may seem unnecessary since this code will always be executed, since 1 is always smaller than 10. However, if instead of the literals 1 and/or 10 we have int variables that change over time or for some reason are unknown at a given time, we can show the usefulness of the if statement. Lets try again:

// Lets say the int variable "a" is a random number. It can be anything.
if (a < 10) {
	cout << "a is smaller than 10" << endl;

In this case, the execution depends on a.

Every if statement has the following form:

if (boolean expression) {
	one or more statements

5.2 If/Else Statements

// the int variable a is a random number.
if (a < 10) {
	cout << "a is smaller than 10" << endl;
else if (a == 10) {
	cout << "a is equal to 10" << endl;
else {
	cout << "a is greater than 10" << endl;

5.3 Switch Statements

// the int variable a holds a random number.
switch(a) {
	case 0:
		cout << "a holds the value 0" << endl;
	case 1:
		cout << "a holds the value 1" << endl;
		cout << "a holds none of the above" << endl;

The switch statement body consists of a series of case labels and an optional default label. Two cases can not evaluate to the same value and the default label may only appear once.

5.4 The Ternary Conditional

This is a very interesting conditional statement. The basic syntax is:

boolean expression ? value if true : value if false

We will start by showing an example of a small program using the ternary conditional in different ways:

#include <iostream>

int main() {
	int a = 0;
	int b = 1;
	int c = a < b ? b : a;

	std::cout << c << std::endl;
	std::cout << (a < b ? "a is smaller" : "b is smaller than or equal to a")
		<< std::endl;
	return 0;

This program prints the following.

a is smaller

5.5 Boolean expressions

Expressions that can evaluate to either true or false are called boolean expressions. A boolean expression often contains comparison operators. These are:

Comparison operators in C++:

	Syntax    Example syntax    Name

	==        a == b            Equal to
	!=        a != b            Not equal to
	>         a > b             Greater than
	<         a < b             Less than
	>=        a >= b            Greater than or equal to
	<=        a <= b            Less than or equal to

Boolean expressions may also contain logical operators.

Logical operators in C++:

	Syntax    Example syntax    Name

	!         !a                not
	&&        a && b            and
	||        a || b            or

6.0 Loops

There are various sorts of loops in C++. Loops are simply used to repeat some statements. Make sure you understand conditional statements before reading any further.

6.1 While Loops

The most fundamental loop is the while loop.

6.2 For Loops

6.3 Do Loops

7.0 Functions