UNIONS

UNIONS

Unions are similar to structures except the fact that memory allocated for a union variable is memory required for the largest field.

The only difference between the structure and union is memory allocation.

Syntax:

          Union unionname

          {

                   Datamember1;

                   Datamember2;

          };

Example

#include<stdio.h>

#include<conio.h>

union emp

{

          char name[25];

          int idno;

          float salary;

}e1;

void main()

{

          printf("Size of union is %d",sizeof(e1));

}

Output

Size of union is 25

Example

#include<stdio.h>

#include<conio.h>

union emps

{

          double a;

          float b[2];

          char c[8];

}e1;

void main()

{

          int i;

          clrscr();

          e1.a=1355.674;

          e1.b[0]=2.3;

          e1.b[1]=4.5;

          printf("Enter 8 characters string:");

          for(i=0;i<8;i++)

                   scanf("%c",&e1.c[i]);

          printf("%.3lf\n",e1.a);

          printf("%.2f,%.2f\n",e1.b[0],e1.b[1]);

          for(i=0;i<8;i++)

                   printf("%c\n",e1.c[i]);

          getch();

}

Output:

Enter 8 characters string: asdgghjk

2.713061780997133810000000000000000000000e+209

1078827923249377390000000.00,283381667918681262000000000.00a

s

d

g

g

h

j

k

it allocates memory only to the largest data type size. In this situation it allocates memory to string, the rest two values double and float values are garbage values.