What happens if I define a 0-size array in C/C++?

Question

Just curious, what actually happens if I define a zero-length array int array[0]; in code? GCC doesn\'t complain at all.

Sample Program

Answer 1

It's totally illegal, and always has been, but a lot of compilers neglect to signal the error. I'm not sure why you want to do this. The one use I know of is to trigger a compile time error from a boolean:

char someCondition[ condition ];

If condition is a false, then I get a compile time error. Because compilers do allow this, however, I've taken to using:

char someCondition[ 2 * condition - 1 ];

This gives a size of either 1 or -1, and I've never found a compiler which would accept a size of -1.