Function string_vsprintf_get_buffer_size

src/hz/string_sprintf.h:93–108

inline int string_vsprintf_get_buffer_size(const char* format, std::va_list ap)
{
#if defined ENABLE_GLIB && ENABLE_GLIB
	// the glib version returns gsize
	return static_cast<int>(g_printf_string_upper_bound(format, ap));

#else
	// In C++11, vsnprintf() returns the number of bytes it could have written
	// (without \0) if buffer was large enough.
	// This includes mingw/ISO.
	const int size = std::vsnprintf(nullptr, 0, format, ap);  // C99 and others
	if (size < 0)
		return -1;
	return size + 1;  // that +1 is for \0.
#endif
}