talker.c

老师上课演示的在Linux上运行的网络聊天小程序,很有启发.

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/socket.h>
#include <sys/wait.h>

#define MYPORT 4950  //端口号
int main (int argc,char *argv[])
{
	int sockfd;
	struct sockaddr_in their_addr;
	struct hostent *he;
	int numbytes;
/*若不是三个传入参数则提示出错信息,并结束运行*/
	if (argc!=3)
	{
		fprintf(stderr,"usage:talker hostname message\n");
		exit(1);
	}
 /*从第二个传入参数获取主机信息*/
        if ((he=gethostbyname(argv[1]))==NULL)
	{
		perror("gethostbyname");
		exit(1);
	}
 /*创建一个socket,赋值给sockfd,创建成功则继续,否则输出出错信息并结束运行*/
	if ((sockfd=socket(AF_INET,SOCK_DGRAM,0))==-1)
	{
		perror("socket");
		exit(1);
	}
	their_addr.sin_family=AF_INET;  //设定地址簇类型
	their_addr.sin_port=htons(MYPORT);  //给端口赋值
	their_addr.sin_addr=*((struct in_addr *)he->h_addr);  //给IP地址赋值
	bzero(&(their_addr.sin_zero),8);
  /*向对方发送消息,消息内容为第三个传入参数的值*/
	               if ((numbytes=sendto(sockfd,argv[2],strlen(argv[2]),0,(struct sockaddr*)&their_addr,sizeof(struct sockaddr)))==-1)
	{
		perror("sendto");
		exit(1);
	}
	printf("send %d bytes to %s \n",numbytes,inet_ntoa(their_addr.sin_addr));
	close(sockfd); //关闭socket
	return 0;
}