Union in C

Union is a user-defined data type that is used to hold the different types of elements like structure. In union, all members share the same memory location. Syntax:

union [union name]
 {
 member definition;
 member definition;
 ...
 member definition;
 };

Example

#include <stdio.h>
union employe{
 //defining a union
 int id;
 char name[32];
 float salary;
} uemp;
struct structure_emp{
 char name[32];
 float salary;
} sJob;
int main()
{
 printf("size of union = %d", sizeof(uemp));
 printf("\nsize of structure = %d", sizeof(sJob));
 return 0;
}

Output

size of union = 32
size of structure = 36

  Difference between C structure and C union

C Structure	C Union
It allocates storage space for all its members separately.	It allocates one common storage space for all its.
It occupies height memory space.	It occupies lower memory space over the structure.
All the member can be accessed at a time	Only one member can be accessed at a time
Example: struct employe { int id; char name[40]; float salary; };	Example: union employe { int id; char name[40]; float salary; };