Union
Union is user defined data type which is use to store a data
member from more than one data member. Followings are some key point about
union
- Union is also a user defined data type But only one member can be saved at a time
- A common space allocated for all member
- Only one member can be initialized at a time.
- Space allocated equal to higher member allocated space.
- Only one member value can be read or write at ones.
- Uses rate is lower than structure due common space allocation.
- If a member initialized and another attempt for change value of other member lead loss of previous value.
#include<stdio.h>
union emp
{
int roll;
char nm[10];
char city[10];
};
void main()
{
union emp ob2;
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);
}
Enum
Enumerate is user defined data type which is integer value assign to a data member as its options. Enumerate is useful to provide user friendly name for available integer options used as some setting of application. For example if an application has shown available color to its window by integer number as we have seen in dos color command.
So for change color you need to remember color code which increase
complexity. By using enumeration you provide color name in user friendly mode.
i.e. Color.Red,Color.Blue instead of integer code.
System will find the correspondence integer related to given color by enumeration
definition.
