Question

Is it possible to globally disable NUL-terminated strings in GCC?

I am using my own string library, and I have absolutely no need for the final NUL characters as it already stores the proper length internally in a struct.

However, if I wanted to append 10 strings, this would mean that 10 bytes are unnecessarily allocated on the stack. With wide strings it is even worse: As for x86, there are 40 bytes wasted; and for x86_64, 80 bytes!

I defined a macro to add those stack-allocated strings to my struct:

#define AppendString(ppDest, pSource) \
  AppendSubString(ppDest, (*ppDest)->len + 1, pSource, 0, sizeof(pSource) - 1)

Using sizeof(...) - 1 works quite well but I am wondering whether I could get rid of NUL termination in order to save a few bytes?

Answer 1

This is pretty awful, but you can explicitly specify the length of every character array constant:

char my_constant[6] = "foobar";
assert(sizeof my_constant == 6);

wchar_t wide_constant[6] = L"foobar";
assert(sizeof wide_constant == 6*sizeof(wchar_t));