修改后 简单的 UDP client

/*

 ============================================================================

 Name        : UDPclient.c

 Author      : vestinfo

 Version     : 1.1

 Copyright   : www.cnblogs.com/vestinfo

 Description : A simple UDP client, Ansi-style

 ============================================================================

 */



#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <unistd.h>

#include <fcntl.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <sys/socket.h>





#define REMOTEPORT 8888

#define REMOTEIP "127.0.0.1"



#define CLIENT_PORT 9999

#define CLIENT_IP "192.168.77.172"



#define MAXLENGTH 256



int main(int argc,char *argv[])

{

	int sockfd;

	char msg[MAXLENGTH];

	struct sockaddr_in servaddr;

	struct sockaddr_in clientaddr;

	socklen_t addr_len;

	addr_len = sizeof(servaddr);



	/* 创建数据报套接字 */

	if(( sockfd = socket(AF_INET,SOCK_DGRAM,0))<0)

	{

		perror("error");

		exit(1);

	}



	/* 绑定client的地址和端口，也可不绑定由内核指定 */

	bzero(&clientaddr, sizeof(clientaddr));

	clientaddr.sin_family = AF_INET;

	clientaddr.sin_port = htons(CLIENT_PORT);

	clientaddr.sin_addr.s_addr = inet_addr(CLIENT_IP);

	if(bind(sockfd, (struct sockaddr *)&clientaddr, sizeof(clientaddr)) < 0)

	{

		perror("error");

		exit(1);

	}



	/* server的地址结构 */

	bzero(&servaddr,sizeof(servaddr));

	servaddr.sin_family = AF_INET;

	servaddr.sin_port = htons(REMOTEPORT);

	servaddr.sin_addr.s_addr = inet_addr(REMOTEIP);



	while(1)

	{

		bzero(msg, MAXLENGTH);

		printf("please input msg\n");

		read(STDIN_FILENO, msg, MAXLENGTH);													//从键盘（终端）键入msg



		sendto(sockfd, msg, strlen(msg), 0, (struct sockaddr *)&servaddr, addr_len);		//发送msg给目的套接字addr



		recvfrom(sockfd, msg, MAXLENGTH, 0, (struct sockaddr *)&servaddr, &addr_len);	//接受目的套接字传来的msg

		printf("Received message from server:%s\n",msg);

	}



}