Why we are no use union instead of Structure?

Question

C++

Answer 1

yeah right... in union ,only one member is accessed at a time ,it has more ambiguity......

Answer 2

bcoz structure has following advantages :
each member have their own memory space, it has less ambiguity, all members of structure can be accessed at a time......

Answer 3

yeah this is right answer

Answer 4

in Union which member have larger data types it will becomes Union's size all member use that memory.......but in structure every member have its own memory and access any time........am I right?