ftp客户端c++编程FTP协议将使用两条单独的TCP连接，一条专用于发送FTP命令，另一条则专用于传递数据。初始建立连接时，服务器在21号端口上接收来自客户端的命令连接。-ftp client c programming FTP will use two separate TCP connection, a dedicated FTP to send orders, and the other one is dedicated to data transfer. The initial est