Q What are the differences between a union and a structure?
A Basically, the difference between a union and a structure is that the members in a union are overlaid and they share the same memory location, whereas the members in a structure have their own memory locations. A union can be referenced by using one of its member names.
Q What will happen if you initialize all members of a union together?
A The value that is assigned to a union member last will be the value that stays in the memory storage of the union until the next assignment to the union. In ANSI C, you can initialize a union by initializing its first member.
Q How do you reference a union member?
A If the name of a union is used to reference the union members, then the dot operator (.) can be used to separate the union name and the name of a union member. If a pointer, which points to a union, is used to reference the union members, then the arrow operator (->) can be used between the pointer name and the name of a union member.
structure.
Can you access the same memory location with different union members?
A Yes. Since all union members in a union share the same memory location, you can access the memory location with different union members. For example, in the program in Listing 20.4, two character constants are assigned to a union memory storage through one of the union members. The two characters saved at the memory location of the union are printed out with the help from another union member.
