Difference between structures and union in c Language?

Answer 1

Structure: Structure is a combination elements, which can be predefined data types or other structure. The length/size of the structure is the sum of the length of its elements.

In C, structures cannot containn functions. in C++ it can.

Union: Union is a combination elements, which can be predefined data types or other union . But, the size/length of union is the maximum of internal elements.

the sizeof() operator returns the size slightly more than calculated size due to padding, which again depends on OS

Answer 2

In case of Structure all members use different memory space, but in Union they use same memory location.

for example

struct abc

{

int x;

char s;

}stru;

union abc

{

int x;

char s;

}stru;

now here in structure it occupies 3 bytes 2 for int, 1 for char but union occupies only 2 bytes ..