C - Data Types

One of the most important parts of learning any programming language is to understand what are the available data types, and how data is stored, accessed and manipulated in that language. Based on the data type of a variable, the operating system allocates memory to the variable and decides what can be stored in the reserved memory.

There are three types of data types in C which are categorized below:

Category	Data Types
Basic Data Type	integer, character, floating point, double floating point, etc.
Derived Data Type	array, pointer, function, reference, etc.
User Defined Data Type	structure, union, enum, typedef, etc.

The table below describes basic data types of C in detail:

Category	Data Types
character	char
Integer	int
Floating Point	float
Double Floating Point	double
The Void Type	void

There are several types of modifier which can be used to modify the data types in C.

signed
unsigned
short
long

The table below describes the variable type, memory size, format specifier, and maximum and minimum value which can be stored in the variable.

Category	Memory Size	Format Specifier	Range
char	1 byte	%c	-128 to 127
unsigned char	1 byte	%c	0 to 255
signed char	1 byte	%c	-128 to 127
short int	2 byte	%hd	-32,768 to 32,767
unsigned short int	2 byte	%hu	0 to 65,535
signed short int	2 byte	%hd	-32,768 to 32,767
int	4 byte	%d	-2,147,483,648 to 2,147,483,647
unsigned int	4 byte	%u	0 to 4,294,967,295
signed int	4 byte	%d	-2,147,483,648 to 2,147,483,647
long int	8 byte	%ld	-2,147,483,648 to 2,147,483,647
unsigned long int	8 byte	%lu	0 to 4,294,967,295
signed long int	8 byte	%ld	-2,147,483,648 to 2,147,483,647
long long int	8 byte	%lld	-(2⁶³) to (2⁶³)-1
unsigned long long int	8 byte	%llu	0 to 18,446,744,073,709,551,615
float	4 byte	%f	1.2E-38 to 3.4E+38 (~6 digits precision)
double	8 byte	%lf	2.3E-308 to 1.7E+308 (~15 digits precision)
long double	16 byte	%Lf	3.4E-4932 to 1.1E+4932 (~19 digits precision)
void	1 byte	%p	void

sizeof() function

The memory size of a data type might be different as shown in the above table, depending upon the particular platform. To find out the size of a data type, sizeof() function can be used.

#include <stdio.h>
 
int main (){
  printf("Size of char: %ld\n", sizeof(char));
  printf("Size of short int: %ld\n", sizeof(short int));
  printf("Size of int: %ld\n", sizeof(int));
  printf("Size of long int: %ld\n", sizeof(long int));
  printf("Size of float: %ld\n", sizeof(float));
  printf("Size of double: %ld\n", sizeof(double));
  printf("Size of void: %ld\n", sizeof(void));
  return 0;
}

The output of the above code will be:

Size of char: 1
Size of short int: 2
Size of int: 4
Size of long int: 8
Size of float: 4
Size of double: 8
Size of void: 1