一个好用的C++日志产生类，不但好用，而且它也很老，好像是老外写的，虽然这么多年了，但还是有很多人在用这个日志类。-A the nice C++ log generated class, not only easy to use, and it is also very old, as if written by a foreigner, so many years, but there are still a lot of people use this log class.