memset(&state, 0, sizeof(state));
num_wchars = mbsrtowcs(wcs, &src, num_wchars + 1, &state);
assert(num_wchars != (size_t)-1);
memset(&state, 0, sizeof(state));
num_wchars = mbsrtowcs(wcs, &src, num_wchars + 1, &state);
assert(num_wchars != (size_t)-1);