说明：  DES加密聊天工具，共包含3个文件：chat.cpp、des.h、makefile。 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。 运行：命令行模式下输入 ./chat，然后选择程序执行角色（客户端或服务器）。如选择服务器，则程序自动打开端口开始监听；如选择客户端，则需要输入服务器地址。最后输入命令quit退出程序。
(DES encrypted chat tool, contains a total of 3 files: chat.cpp, des.h, makefile. Compile: Command line mode, switch to the code directory, type make after the press Enter. Run: command line, type./Chat, and then select the program execution role (client or server). If you choose the server, the program automatically opens the port to start listening If you choose a client, you need to enter the server address. Finally, enter the command quit to exit the program.)