Both the structures and unions are syntactically and functionally same, however, they differ in the way memory is allocated to their members. While declaring structure variables, the different members are stored in different, although, adjacent memory locations whereas different members of a union variable share the same memory location. The amount of memory sufficient to hold the largest member of a union is allocated to a union variable. Thus, a union enables the same block of memory to store variable of one type at one time and of different type at another time. To understand the concept of memory allocation to a union, consider these statements.