#include <unistd.h>#include <sys/socket.h>#include <sys/types.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <errno.h>#include <netinet/in.h>#include <netdb.h>#define  PORT 3333#define  MAXDATASIZE 100main(int argc,char *argv[]){  int sockfd,sendbytes;  char buf[MAXDATASIZE];  struct hostent *host;  struct sockaddr_in serv_addr;   if(argc<2){  fprintf(stderr,"please enter the server's hostname\n");  exit(1);    }   if((host=gethostbyname(argv[1]))==NULL){  perror("gethostbyname");  exit(1);    }  if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1){    perror("socket");    exit(1);  }  serv_addr.sin_family=AF_INET;  serv_addr.sin_port=htons(PORT);  serv_addr.sin_addr=*((struct in_addr *)host->h_addr);  bzero(&(serv_addr.sin_zero),8);     if(connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(struct sockaddr))==-1){  perror("connect");  exit(1);    }   if((sendbytes=send(sockfd,"peims nihao",15,0))==-1){  perror("send");  exit(1);  }  close(sockfd);}