Difference between Structure and Union

Sr No.	Structure	Union
1	Structure is user defined data type Which store a record with multiple value	Union is also a user defined data type But only one member can be saved at a time
2	Separate space was allocated for each member of structure	A common space allocated for all member
3	All members can be initialized at ones.	Only one member can be initialized at a time.
4	Total memory allocated by a structure variable is equal to number of member allocated space.	Space allocated equal to higher member allocated space.
5	One can provide and used all member data simultaneously.	Only one member value can be read or write at ones.
6	Uses rate of structure is higher due to separate space allocation for each member.	Uses rate is lower than structure due common space allocation.
7	You can updated previous value of any member without losing other member data	If a member initialized and another attempt for change value of other member lead loss of previous value.

#include<stdio.h>

struct stu

{

     int roll;

     char nm[10];

     char city[10];

};

union emp

{

     int roll;

     char nm[10];

     char city[10];

};

void main()

{

     struct stu ob1;

     union emp ob2;

     clrscr();

     ob1.roll=101;

     strcpy(ob1.nm,"Girfa");

     strcpy(ob1.city,"Student Help");

     printf("\nSize of Structure %d",sizeof(ob1));

     printf("\n\tRoll=%d\n\tName=%s\n\tCity=%s",ob1.roll,ob1.nm,ob1.city);

     ob2.roll=101;

     printf("\nSize of Union\t %d",sizeof(ob2));

     printf("\nUnion Roll %d",ob2.roll);

     strcpy(ob2.nm,"Girfa");

     printf("\nValue Loss due to Union  %d",ob2.nm);

     getch();

}

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