C++ Data Types

In this tutorial, we will learn about basic data types such as int, float, char, etc. in C++ programming with the help of examples.

In C++, data types are declarations for variables. This determines the type and size of data associated with variables. For example,

int age = 13;

Here, age is a variable of type int. Meaning, the variable can only store integers of either 2 or 4 bytes.

C++ Fundamental Data Types

The table below shows the fundamental data types, their meaning, and their sizes (in bytes):

Data Type	Meaning	Size (in Bytes)
`int`	Integer	2 or 4
`float`	Floating-point	4
`double`	Double Floating-point	8
`char`	Character	1
`wchar_t`	Wide Character	2
`bool`	Boolean	1
`void`	Empty	0

Now, let us discuss these fundamental data types in more detail.

1. C++ int

The int keyword is used to indicate integers.
Its size is usually 4 bytes. Meaning, it can store values from -2147483648 to 2147483647.
For example,

int salary = 85000;

2. C++ float and double

float and double are used to store floating-point numbers (decimals and exponentials).
The size of float is 4 bytes and the size of double is 8 bytes. Hence, double has two times the precision of float. To learn more, visit C++ float and double.
For example,

float area = 64.74;
double volume = 134.64534;

As mentioned above, these two data types are also used for exponentials. For example,

double distance = 45E12    // 45E12 is equal to 45*10^12

3. C++ char

Keyword char is used for characters.
Its size is 1 byte.
Characters in C++ are enclosed inside single quotes ' '.
For example,

char test = 'h';

Note: In C++, an integer value is stored in a char variable rather than the character itself. To learn more, visit C++ characters.

4. C++ wchar_t

Wide character wchar_t is similar to the char data type, except its size is 2 bytes instead of 1.
It is used to represent characters that require more memory to represent them than a single char.
For example,

wchar_t test = L'ם'  // storing Hebrew character;

Notice the letter L before the quotation marks.

Note: There are also two other fixed-size character types char16_t and char32_t introduced in C++11.

5. C++ bool

The bool data type has one of two possible values: true or false.
Booleans are used in conditional statements and loops (which we will learn in later chapters).
For example,

bool cond = false;

6. C++ void

The void keyword indicates an absence of data. It means "nothing" or "no value".
We will use void when we learn about functions and pointers.

Note: We cannot declare variables of the void type.

Putting it all together

Run the following repl to see its results. Looking at the main.cpp file, a range of variables of different data types are declared at the top.

cout is used with the + operator to output the sum of two integers. cout is also used to display a message that includes the contents of the string variables, and lastly an if statement is used to present a message based on which letter is stored in the char variable.

Try doing each of the following, running the between each change:

Change the string variables to reflect your name
Change the values of the integers
Change the operator used in the output to *
Change the letter stored in the char variable to a grade you would like to receive
Change the integer variables to float, and assign decimal values.

C++ Type Modifiers

We can further modify some of the fundamental data types by using type modifiers. There are 4 type modifiers in C++. They are:

signed
unsigned
short
long

We can modify the following data types with the above modifiers:

int
double
char

C++ Modified Data Types List

Data Type	Size (in Bytes)	Meaning
`signed int`	4	used for integers (equivalent to `int`)
`unsigned int`	4	can only store positive integers
`short`	2	used for small integers (range -32768 to 32767)
`unsigned short`	2	used for small positive integers (range 0 to 65,535)
`long`	at least 4	used for large integers (equivalent to `long int`)
`unsigned long`	4	used for large positive integers or 0 (equivalent to `unsigned` `long int`)
`long long`	8	used for very large integers (equivalent to `long long int`).
`unsigned long long`	8	used for very large positive integers or 0 (equivalent to `unsigned long long int`)
`long double`	12	used for large floating-point numbers
`signed char`	1	used for characters (guaranteed range -127 to 127)
`unsigned char`	1	used for characters (range 0 to 255)

Let's see a few examples.

long b = 4523232;
long int c = 2345342;
long double d = 233434.56343;
short d = 3434233; // Error! out of range
unsigned int a = -5;    // Error! can only store positive numbers or 0

Derived Data Types

Data types that are derived from fundamental data types are derived types. For example: arrays, pointers, function types, structures, etc.

We will learn about these derived data types in later tutorials.