What is the difference between union and struct in C++?

In C++, both union and struct are keywords used to define custom data types.

1. Structural organization:

1. struct is used to define a data structure containing members of different data types.
2. Each member of the struct occupies its own independent memory space.
3. The members within a struct can coexist and their memory addresses are contiguous.
4. Structures can have member functions that can manipulate the data within the structure.

1. union: a collective body

1. The union is also used to define a data structure that contains members of different data types.
2. All members in the union share the same memory space.
3. Only one member of the union can exist and be used at a time.
4. The size of the union is determined by its largest member.
5. Unions cannot have function members.

Therefore, structs are suitable for situations where different types of data need to be stored simultaneously, with each member occupying separate memory space; while unions are suitable for situations where memory space needs to be saved, with different members sharing the same block of memory.