string_format

std::string string_format(const std::string fmt, ...) {
	int size = 100;
	std::string str;
	va_list ap;
	while (1) {
		str.resize(size);
		va_start(ap, fmt);
		int n = vsnprintf((char *)str.c_str(), size, fmt.c_str(), ap);
		va_end(ap);
		if (n > -1 && n < size) {
			str.resize(n);
			return str;
		}
		if (n > -1)
			size = n + 1;
		else
			size *= 2;
	}
	return str;
}

std::wstring wstring_format(const std::wstring fmt, ...) {
	int size = 100;
	std::wstring str;
	va_list ap;
	while (1) {
		str.resize(size);
		va_start(ap, fmt);
		
		int n = _vsnwprintf((wchar_t *)str.c_str(), size, fmt.c_str(), ap);
		va_end(ap);
		if (n > -1 && n < size) {
			str.resize(n);
			return str;
		}
		if (n > -1)
			size = n + 1;
		else
			size *= 2;
	}
	return str;
}