C - Data Types

Data type specifies the type of data, entered by the user. Data types are divided into two major categories:

Primary Data Type

Secondary Data Type

Primary Data Type

Primary data type are also known as Primitive or Pre-defined data types. It is divided into 3 categories.

Integral (Non-Decimal): Only integer values are allowed.
Real (Decimal): In Real data type, decimal values can be used.
Character: Character data type can store only single character.

Integral (Non-Decimal) Data Type
Data Type	Size	Format	Range
int short signed signed int	2 Bytes	%d	-32768 to 32767
unsigned int unsigned short int	2 Bytes	%u	0 to 65535
long long int	4 Bytes	%ld	-2147483648 to 2147483647
unsigned long	4 Bytes	%lu	0 to 4294967295
long long int	8 Bytes	%ld	-2⁶³ to 2⁶³-1

Real (Decimal) Data Type
Data Type	Size	Format	Range
float	4 Bytes	%f	-3.4e³⁸ to 3.4e³⁸
double	8 Bytes	%lf	-1.7e³⁰⁸ to 1.7e³⁰⁸
long double	10 Bytes	%LF	-1.7e⁴⁹³² to 1.7e⁴⁹³²

Character Data Type
S.No.	Data Type	Size	Format	Range
	char	1 Byte	%c	0 to 255
	array of char (string)	Depends on declaration	%s	Depends on declaration

Note: The memory size of basic data types may change according to 32 or 64 bit operating system. The above mentioned size is given according to 32 bit OS.

User-Defined Data Types

2. Secondary / Non – Primitive / User Defined Data Types : These data types are defined and use by user according to his requirements. Secondary data types are:

Arrays: collection of values of similar data types.
Pointers: hold the address of a variable
Structure: combine different data types which are related.
Union: Same as structure but it saves memory
Enum: assign number to names
Typedef: Alias of pre-defined data type.