c++ - size of pointers and architecture

By conducting a basic test by running a simple C++ program on a normal desktop PC it seems plausible to suppose that sizes of pointers of any type (including pointers to functions) are equal to the target architecture bits ?

For example: in 32 bits architectures -> 4 bytes and in 64 bits architectures -> 8 bytes.

However I remember reading that, it is not like that in general!

So I was wondering what would be such circumstances?

• For equality of size of pointers to data types compared with size of pointers
  to other data types


• For equality of size of pointers to data types compared with size of pointers
  
  to functions


• For equality of size of pointers to target architecture