用置换的方法对文件进行加密，采用C语言实现，简单的一个例子，对于学习是很有帮助的。-replacement with the right documents encrypted using C language, a simple example, the study is very helpful.

这是网络编程使用的源代码，对学习c语言的同学会有很大的帮助-It is used in network programming source code, to learn c language will be very helpful for students