BITFIELDS

BITFIELDS:

           

A bitfield is a set of adjacent bits whose size can be from 1 to 16 bits. Bit field provides exact amount of bits required to store values i.e., for example when an integer is declared, 2 bytes are allocated to store an integer which we may or may not completely utilize.

             Therefore, to avoid wastage of memory, we mention the exact bit size. The name and size of bit fields are defined using a structure.

Syntax:-

struct tagname

{

datatype member 1:bit length;

datatype member 2:bit length;

:

:

datatype member n:bit length;

};

·         Here, the datatype can be either int or unsigned int or signed int.

·         Bit length specifies the number of bits used under that name.

·         Here the colon(:) tells the compiler that bitfields are used in the structure.

·         In a bitfield of lenght1 we can store the values 0,1.

·         In a bitfield of lenght2 we can store the values 0,1,2,3.

·         Similarly, in a bit field of lenght1 we can store the values 0,to 2ⁿ-1.

Ø  A Program to implement bitfields.

#include<stdio.h>

            #include<conio.h>

            void main( )

            {

struct employee

{

unsigned  empid:6;

unsigned age:5;

unsigned children:2;

        }e1;

                  clrscr( );

e1.empid=59;

e1.age=29;

e1.children=2;

printf(“details are\n”);

printf(“%u %u %u”,e1.empid,e1.age,e1.children);

getch( );

}