Note that the data type sizes don’t need to match, so it’s no problem to have a union with, for example, a 32-bit and a single 8-bit integer, the 8-bit value is simply truncated if needed.

If you program in C, strings are just in your imagination. What you really have is a character pointer, and we all agree that a string is every character from that point up until one of the charact… ...

GCC implemented zero-length arrays years prior to C99; the syntax was type name [0]. The two are equivalent, but you should prefer the empty array operator as it is now standardized.