C编写，实现字符串摘要、文件摘要两个功能。

里面主要包含3个文件: Md5.cpp、Md5.h、Main.cpp。其中Md5.cpp是算法的代码，里的代码大多是从 rfc-1321 里copy过来的；Main.cpp是主程序。 -C prepared, the realization of string summary document containing a summary of two functions. Which mainly includes three documents: Md5.cpp, Md5.h, Main.cpp. Md5.cpp algorithm which is the code in the code are from the rfc-1321-ri copy back　Main.cpp is the main program.