Data Types

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.

 

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
bool	Boolean	1
void	Empty	0

 

1.  int

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

 

2. 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.

Example

float area = 64.74;

double volume = 134.64534;

3. char

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

Example

char test = ‘p’ ;

 

4. 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).

Example

Bool cond = false;

 

5. 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.

 

 

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:

1. signed
2. unsigned
3. short
4. long

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

• int
• double
• char

 

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)

 

Derived Data Types

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