Data Types

            In C programming languages, a data type tells to the compiler about which the type of data is going to be stored and the compiler reserves the fixed number of bytes for that particular data (i.e. variable or constant).

we can say that, a data type defines two things:

1. Type of data (i.e. Primary (int,char,float & void) , derived ( i.e. Array, function & pointer) , User define (i.e. structure, union & enum)
2. Memory blocks to be reserved for the data.

Data types are classified in three types i.e. Primary data type, derived data type & User define data type.

Units of Memory

0 or 1 – 1 bit

Group of 4 bits = 1 nibble

Group of 8 bits = 1 bytes

·        Primary Data types:

There are 4 primary or basic data types in C.

1)     Integer type:

§  It contains integer numbers.

§  To represent integer data type we use int keyword in C.

 

Sr. No.	Data Type	Size in Memory	Keyword	Format Specifier	Range
1	integer or sign integer	2  Bytes	int	%d	-32768 to 32767
2	Unsigned integer	2 Bytes	unsigned	%u	0 to 65535
3	Short integer	1 Byte	short int (or short )	%hd	-128 to 127
4	Unsigned short integer	1 Byte	unsigned short	%hu	0 to 255
5	long integer or Sign long integer	4 Bytes	long int (or long)	%ld	-2,147,483,648 to 2,147,483,647
6	Unsigned long integer	4 Bytes	unsigned long int (or unsigned long)	%lu	0 to 4,294,967,295

 

 

1)     Floating type:

§  Floating type contains decimal point (fractional numbers)

§  Floating point data type stored in 4 byte (32 bit) memory with 6 digit precision.

§  In float number after point numbers of digit is present is called precision

 

Sr. No.	Data Type	Size in Memory	Format Specifier	Range
1	float	4  Bytes	%f	3.4 e -38 to 3.4 e +38
2	double	8 Bytes	%lf	1.7 e -308 to 1.7 e +308
3	long double	10 Byte	%Lf	3.4 e -4932 to 1.1 e +4932

 

2)     Character data type:

§  Character type is define as a char

Sr. No.	Data Type	Size in Memory	Format Specifier	Range
1	char or signed char	1Bytes	%c	-128 to 127
2	char or unsigned char	1 Bytes	%c	0 to 255

 

Note – empty data type is called void data 

----------------------------------------------------------

// Program to showing size of different DATA TYPES

 

#include<stdio.h>

#include<conio.h>

void main()

{

           clrscr();

 

           printf("\n * Output of program to showing size of different DATA TYPES *\n");

           printf("\n   size of integer = %d",sizeof(int));

           printf("\n   size of unsigned integer = %d",sizeof(unsigned));

           printf("\n   size of long integer = %d",sizeof(long));

           printf("\n   size of unsigned long integer = %d",sizeof(unsigned long));

           printf("\n   size of float = %d",sizeof(float));

           printf("\n   size of double = %d",sizeof(double));

           printf("\n   size of long double = %d",sizeof(long double));

           printf("\n   size of character = %d",sizeof(char));

           printf("\n   size of unsigned character = %d",sizeof(unsigned char));

 

           getch();

}

 

·        Derived data type

1)     Array:

§  Collection of similar data type is called array.

2)     Function:

§  Outside of main function subprogram is written is called function.

3)     Pointer:

§  Pointer is variable which holds address of another variable.

·        User define data type

1)     Structure / Union :

§  It is collection of different data type.

2)     Enum :

Enum (or Enumeration) is used to assign names to integral constants.