ftp客户端是一个比较简单的ftp程序，但是程序提供了各种接口，能够让读者看法出各种复杂的ftp程序，程序中的各个程序模块均已经实现；-ftp client is a relatively simple ftp program, but the program offers a variety of interface, that allows readers to view a variety of complex ftp procedures, procedures for the vari