A struct is a group of complex data structures stored in a block of memory where each member on the block gets a separate memory location to make them accessible at once
Whereas in the union, all the member variables are stored at the same location on the memory as a result to which while assigning a value to a member variable will change the value of all other members.
/* struct & union definations*/
struct bar {
int a; // we can use a & b both simultaneously
char b;
} bar;
union foo {
int a; // we can't use both a and b simultaneously
char b;
} foo;
/* using struc and union variables*/
struct bar y;
y.a = 3; // OK to use
y.b = 'c'; // OK to use
union foo x;
x.a = 3; // OK
x.b = 'c'; // NOl this affects the value of x.a!
