STL之string 格式化的自我实现

template<typename ... Args>
static std::string FormatString(const std::string& format, Args ... args)
{
	auto size = std::snprintf(nullptr, 0, format.c_str(), args ...) + 1; // Extra space for '\0'
	std::unique_ptr<char[]> buf(new char[size]);
	std::snprintf(buf.get(), size, format.c_str(), args ...);
	return std::string(buf.get(), buf.get() + size - 1); // We don't want the '\0' inside
}

template<typename ... Args>
static std::wstring FormatString(const std::wstring& format, Args ... args)
{
	auto size = std::swprintf(nullptr, 0, format.c_str(), args ...) + 1; // Extra space for '\0'
	std::unique_ptr<wchar_t[]> buf(new wchar_t[size]);
	std::swprintf(buf.get(), size, format.c_str(), args ...);
	return std::wstring(buf.get(), buf.get() + size - 1); // We don't want the '\0' inside
}

#define QJFORMAT(fmt,...) FormatString(fmt,__VA_ARGS__)


int main() 
{
	{
		std::string str;
		str = QJFORMAT("%d %s", 110, "hello wrold");
		printf("%s\n", str.c_str());
	}


	{
		std::wstring str;
		str = QJFORMAT(L"%d %s", 110, L"hello wrold");
		printf("%ws\n", str.c_str());
	}
	
	getchar();
	return 0;
}