Union within Structure

Union within Structure

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

struct student

{

            int marks;

            union

            {

                        char name[20];

                        int usn;

            } u;

} s;

main()

{

            int  ch;

            printf("\n Enter marks:");

            scanf("%d", &s.marks);

            printf("\nName or USN choice:");

            printf("\n 1.Name 2.USN: ");

            scanf("%d", &ch);

            switch(ch)

            {

                        case 1:             printf("\nEnter name:");

                                                scanf("%s", s.u.name);

                                                printf("\nYour name is:%s", s.u.name);

                                                break;

                        case 2:             printf("\nEnter usn:");

                                                scanf("%d", &s.u.usn);

                                                printf("\nYour usn is:%d", s.u.usn);

                                                break;

            }

            printf("\nYour marks is:%d", s.marks);

}

Output:

Enter marks: 80

Name or USN choice:

1.Name 2.USN:            1

Enter name: AAAAA

Your name is: AAAAA

Your marks is: 80 

Structure and Union Initialization

Structure and Union Initialization

#include<stdio.h>

struct first

{

            int x, y;

};

union second

{

            int x, y;

};

main()

{

            struct first f1 = {1, 2};

            printf("\nf1.x = %d \t f1.y = %d", f1.x, f1.y);

            union second s1;

            s1.x = 3;

            printf("\ns1.x = %d\t", s1.x);

            s1.y = 4;

            printf("\ns1.y = %d", s1.y);

            union second s2 = {6, 7};

            printf("\ns2.x = %d\t s2.y = %d", s2.x, s2.y);

            union second s3;

            s3.x = 10;

            s3.y = 9;

            printf("\ns3.x = %d\t s3.y = %d", s3.x, s3.y);

}

Output:

f1.x = 1   f1.y = 2

s1.x = 3   s1.y = 4

s2.x = 6   s2.y = 6

s3.x = 9   s3.y = 9

Unions

Module 1: Unions

• The size and address of union

• Union Initialization

• Union Example

The Size and Address of Unions

The Size and Address of Structure and Unions

#include<stdio.h>

#include<stdlib.h>

struct stag

{

            char c;

            int i;

            float f;

            double d;

};

union utag

{

            char c;

            int i;

            float f;

            double d;

};

main()

{

            struct stag s;

            printf("\n size of structure=%u", sizeof(struct stag));

            printf("\n size of structure=%u", sizeof(s));

            printf("\n address of structure=%u", &s);

            printf("\n address of structure members: %u %u %u %u", &s.c, &s.i, &s.f, &s.d);

            union utag u;

            printf("\n size of union=%u",sizeof(union utag));

            printf("\n size of union=%u",sizeof(u));

            printf("\n address of union=%u",&u);

            printf("\n address of union members: %u %u %u %u",&u.c,&u.i,&u.f,&u.d);

}

Output:

 size of structure=24

 size of structure=24

 address of structure=2686752

 address of structure members: 2686752      2686756          2686760          2686768

 size of union=8

 size of union=8

 address of union=2686744

 address of union members: 2686744            2686744          2686744          2686744

Data Structures and Applications(15CS33): Module 1

Data Structures and Applications (15CS33):

Module 1

Click on the respective topics: 

• Structures

• Unions

• Pointers

• Arrays

• Strings

• Dynamic Memory Management