5

代码说明：

说明：  基于MD5的文件完整性检测程序，共包含4个文件：md5.h、md5.cpp、test.cpp、nankai.txt。编译：命令行模式下，切换到代码所在目录，输入make后回车即可。(The file integrity testing program based on MD5 contains 4 files: md5.h, md5.cpp, test.cpp, nankai.txt. Compile: In the command line mode, switch to the directory where the code is located, enter make, and press Enter.)