#include <stdio.h>#include <string.h>#include <errno.h>#include <netinet/in.h>#define PORT 9999#define HOST_ADDR "Beauty.eeis.ustc.edu.cn"main(){	struct sockaddr_in server;	struct hostent *hp;	int s,ns;	int pktlen,buflen;	char buf1[256],buf2[256];	s=socket(AF_INET,SOCK_STREAM,0);	server.sin_family=AF_INET;	server.sin_port=htons(PORT);	hp=gethostbyname(HOST_ADDR);	memcpy(hp->h_addr,&server.sin_addr,hp->h_length);	if(connect(s,(struct sockaddr *)&server,sizeof(server))<0)	{		perror("connect()");		return;	}	for(;;)	{		printf("Enter a line:");		gets(buf1);		buflen=strlen(buf1);		if(buflen==0)			break;		send(s,buf1,buflen+1,0);		recv(s,buf2,sizeof(buf2),0);		printf("Received line: %s\n",buf2);	}	close(s);}