What is class union in c language?

Answer 1

A union is often confused with the structure data-type that can contain multiple data items simultaneously. A union can contain only one piece of data and that data may be of any data type.

struct foo

{

int a;

long b;

float c;

char d[80];

}my_struct;

The structure foo will have space for all the variables.

union bar

{

int a;

long b;

float c;

char d[80];

}my_union;

The union bar will have 80 bytes assigned to it, 80 being the size of the largest variable (char d[80]). At any given time only one variable can be stored in bar.

my_union.a is used to read or write an int.

my_union.b is used to read or write a long.

my_union.c is used to read or write a float.

my_union.d is used to read or write a string.

C does not have classes, C++ has class unions (a union used to define a class). A class union is the same as a union in C but gets its name from how it is used.