client.c

这个资料非常不错

/***********
 * client.c*
 ***********/
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

int main(int argc, char *argv[])
{
int sockfd ,newsockfd, help, sent;
struct sockaddr_in peer;
struct hostent *serverhost;
char buff[5000];


 if(argc<2)
 {
 fprintf(stderr, "Usage: coc <hostname>\n");
 exit(1);
 }

 if ((sockfd = socket(AF_INET,SOCK_STREAM,0)) < 0 )
 {
 perror("socket");
 exit(1);
}


 if((serverhost = gethostbyname(argv[1])) == 0) 
 {
 perror("gethostbyname");
 exit(1);
 }


 peer.sin_family = AF_INET;
 peer.sin_port = htons(10000); 
 peer.sin_addr = *(struct in_addr*)serverhost->h_addr_list[0];

 if (connect(sockfd, &peer, sizeof(peer)) < 0 ) 
 {
 perror("connect");
 exit(1);
 }

 for(help=0; help<sizeof(buff); help++)
 buff[help] = '0'+help%10;

 write(sockfd, buff, 5000);

 close(sockfd);
}