Structures Inside Unions

STRUCTURES INSIDE UNIONS

C also allows users to have a structure within a union. The program given below illustrates the use of structures within a union. There are two structure variables in the union. The size of the union will be size of structure variable which is larger of the two. During run-time, programmer will choose to enter name or roll number of the student and the corresponding action will thus be taken.

#include <stdio.h>

typedef struct a

{ int marks;

char name [20];

};

typedef struct b

{ int marks;

int roll_no;

};

typedef union Student

{ struct a A;

struct b B;

};

main()

{

union Student s;

char ch;

printf("\n Do you want to enter name or roll number of the student : (N/R) - ");

scanf("%c", &ch);

if (ch == 'R')

{

printf("\n Enter the roll number : ");

scanf("%d", &s. B. roll_no);

printf("\n Enter the marks: ");

scanf("%d", &s. B. marks);

}

else

{

printf("\n Enter the name: ");

gets (s.A.name);

printf("\n Enter the marks: ");

scanf("%d", &s.A.marks);

}

printf("\n ****** STUDENT'S DETAILS *******") ;

if (ch == 'N')

{

printf("\n NAME: ");

puts (s.A.name);

printf("\n MARKS: %d", s.A.marks);

}

else

{

printf("\n ROLL NO : %d", s.B. roll_ no);

printf("\n MARKS : %d", s.B.marks);

}

}

Output

Do you want to enter name or roll number of the student : (N/R) – R

Enter the roll number : 12

Enter the marks : 99

****** STUDENT'S DETAILS *******

ROLL NO: 12

MARKS: 99