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。-An easy to use C++ to generate a log class, not only easy to use, but it is also very old, seems to be written by a foreigner, though so many years, but there are still a lot of people use thi