BIT FIELDS IN C-LANGUAGE

BIT FIELDS

            In C language, bits are manipulated in two ways.  Those are:

1. Implementation of Bit-wise Operators:               C language supports Bit-wise AND, Bit-wise OR, Bit-wise Exclusive-OR, One’s complement, Left Shift and Right Shift operators as bit-wise operators that are used for manipulating data at bit level of the operands.

2. Utilization of bit fields within structure:

·         Bit fields provides exact amount of bits required by the variable.

·         Bit fields uses the memory very efficiently.

·         The bits must be specified by non-negative(unsigned) integer type followed by a colon(:).

·         Bit fields can also used as member in unions.

The name and size of bit fields are defined using structure.  For bit fields memory is allocated in adjacent bits.  The general format of bit field definition is:

            Syntax:            struct tag

                                    {

                                                unsigned int member1 : bitwidth1;

                                                unsigned int member2 : bitwidth2;

                                                            - - - - - - 

                                                            - - - - - -

                                                unsigned int membern : bitwidthn;

                                    } variable;

/* Example C program - Bit Fields */

#include <stdio.h>

struct date

{

unsigned int d:5;

unsigned int m:4;

unsigned int y:6;

}dt;

 main()

{

dt.d=20;

dt.m=10;

dt.y=16;

printf("The date is: %d/%d/%d",dt.d,dt.m,dt.y);

getch();

}

Output

The date is: 20/10/16