求教 USER PASS命令
ftp login代码段如下：
login()
{
.....
char buffer[256];
bzero(buffer,sizeof(buffer));
sprintf(buffer, "USER %s\r\n ",user);
send(sock,buffer,sizeof(buffer),0);
recvbuff(sock);


sprintf(buffer, "PASS %s\r\n ",pass);
send(sock,buffer,sizeof(buffer),0);
recvbuff(sock);

return 0;}


int recvbuff(int sock)
{
char buff[1024];
bzero(buff,1024); //清0
int ret = recv(sock,buff,1024,0);
printf(buff);
return 0;
}


结果是
control connect success.
220---------- Welcome to Pure-FTPd [TLS] ----------
220-You are user number 1 of 50 allowed.
220-Local time is now 13:58. Server port: 21.
220-IPv6 connections are also welcome on this server.
220 You will be disconnected after 15 minutes of inactivity.
331 User root OK. Password required
。。。。


谁可以帮忙分析哈是什么原因哦，万分感谢


[解决办法]
看 send 函数的声明及第三个参数的说明，另外分别看一下 sizeof 和 strlen的含义，要是看完了还不懂，就不用给我分了