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);
	}

}