Struct, Consortium, memory allocation

# Include <stdio. h> struct a {char X [6]; int y; char Z [6] ;}; struct B {int y; char X [6]; char Z [6] ;}; Union c {char X [6]; int y; char Z [6] ;}; int main () {printf ("% d, % d, % d \ n ", sizeof (struct a), sizeof (struct B), sizeof (Union C); Return 0 ;}

Running result: 20, 16, 8

Each element in the struct occupies the memory space independently, and the total space is the sum of the space occupied by each element. Although the elements of A and B are the same, the order is different and the memory space occupied by the 4-byte alignment is different.

Each element in the consortium shares a piece of memory space. Only one element can be used at a time. The total space is the space occupied by the largest element (8 in the answer is because 4-byte alignment is taken into account ).

Struct, Consortium, memory allocation