udpcli04.c

/*client.c*/
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <arpa/inet.h>
#define MAXBUF 256
int main(int argc, char const *argv[])
{
	int s = 0;
	int n = 0;
	int reuse = 1;
	int port = 9777;
	struct sockaddr_in srv;
	int srv_len = sizeof(struct sockaddr);
	char buf[MAXBUF] = {0};
	/*解析参数*/
	if (argc != 2)
	{
		printf("Usage:%s ServerIP\n", argv[0]);
		return -1;
	}
 
	bzero(&srv, sizeof(srv));
	srv.sin_family = PF_INET;
	srv.sin_addr.s_addr = inet_addr(argv[1]);
	srv.sin_port = htons(port);
	/*创建 UDP 套节字*/
	s = socket(AF_INET, SOCK_DGRAM, 0);
	if(s<0){
		perror("socket");
		return -1;
	}
 
	printf("----------------------------------------------------------------\n");
	while(1){
		memset(buf, 0, MAXBUF);
		/*读取用户输入到buf中*/
		fgets(buf, MAXBUF, stdin);
 
		/*通过套节字 s 向服务器发送数据*/
		if ((n = sendto(s, buf, strlen(buf), 0, (struct sockaddr *) &srv, sizeof(struct sockaddr))) < 0)
		{
			perror("error sendto");
			return -1;
		}else{
			printf("send to %s(port=%d) len%d: %s", argv[1], port, n-1, buf);
		}

		//从套接字s中读取数据
		if(n = recvfrom(s, buf, MAXBUF, 0, (struct sockaddr *)&srv, &srv_len)<0){
			perror("error recvfrom");
			return -1;
		}else{
			printf("收到%s",buf);
			printf("----------------------------------------------------------------\n");
		}
	}

}