Can there be a C++ type that takes 0 bytes

Question

I\'m trying to declare a C++ variable that takes up zero bytes. Its in a union, and I started with the type as int[0]. I don\'t know if that is actually zero bytes (although

Answer 1

You cannot instantiate any data type in C++ that takes up zero bytes. The Standard dictates than an empty class, such as:

class Empty {};

...will result in the following being true:

Empty emp;
assert( sizeof(emp) != 0 );

The reason for this is so that you can take the address of the object.

EDIT: I originally said the sizeof would be 1, but per @Als' comment, I have found the relevant passage in the Standard, and it is indeed simply non-zero:

[Classes] §9/3

Complete objects and member subobjects of class type shall have nonzero size