XX：那飘过的100~_~{2014/10/03 10:57}

UDP是一种面向非连接SOCK_DGRAM，提供无连接服务。数据包以独立包形式发送，不提供无措保证，数据能够丢失或反复。

UDP的Server和Client的差别相对照较模糊，仅仅要调用 sendto和 recvfrom 就能够给指定的地址收发数据。

1. server端：

// udpClient.cpp : Defines the entry point for the application.

//

#include "stdafx.h"

#include "tchar.h"

#pragma comment(lib,"wsock32.lib")

#include <stdio.h>

#include <winsock2.h>

BOOL InitWinsock();				//Winsock服务初始化

void main()

{

	SOCKET socket1;

	InitWinsock();

	struct sockaddr_in local;

	struct sockaddr_in from;

	int err;

	int fromlean=sizeof(from);

	local.sin_family=AF_INET;

	local.sin_port=htons(1234);					//监听端口

	local.sin_addr.S_un.S_addr=INADDR_ANY;		//本机

	socket1=socket(AF_INET,SOCK_DGRAM,0);

	bind(socket1,(sockaddr *)&local,sizeof local);

	while(true)

	{

		char buffer[1024]="\0";

		printf("waiting for message from others \n");

		err=recvfrom(socket1,buffer,sizeof(buffer),0,(sockaddr *)&from,&fromlean);

		if(err!=SOCKET_ERROR)

		{

			printf("Received from %s--%s\n",inet_ntoa(from.sin_addr),buffer);

			//给Client发信息

			sendto(socket1,buffer,sizeof buffer,0,(sockaddr *)&from,fromlean);

		}

		Sleep(500);

	}

	closesocket(socket1);

}

BOOL InitWinsock()

{

	int Error;

	WORD Version;

	WSADATA Wsa;

	Version=MAKEWORD(2,2);

	Error=WSAStartup(Version,&Wsa);

	if(Error!=0)

	{

		return FALSE;

	}

	else

	{

		if(LOBYTE(Wsa.wVersion)!=2 || HIBYTE(Wsa.wHighVersion)!=2)

		{

			WSACleanup();

			return FALSE;

		}

	}

	return TRUE;

}

2.client

// udpClient.cpp : Defines the entry point for the application.

//

#include "stdafx.h"

#include "tchar.h"

#pragma comment(lib,"wsock32.lib")

#include <stdio.h>

#include <winsock2.h>

BOOL InitWinsock();				//Winsock服务初始化

void main()

{

	SOCKET socket1;

	InitWinsock();

	struct sockaddr_in server;

	int err;

	int lean=sizeof(server);

	server.sin_family=AF_INET;

	server.sin_port=htons(1234);								//服务器的监听端口为1234

	server.sin_addr.S_un.S_addr=inet_addr("192.168.1.18");		//设置为本机地址

	socket1=socket(AF_INET,SOCK_DGRAM,0);

	while(true)

	{

		char buffer[1024]="\0";

		printf("input message \n");

		scanf("%s",buffer);

		if(strcmp(buffer,"bye")==0)

		{

			break;

		}

		err=sendto(socket1,buffer,sizeof(buffer),0,(sockaddr *)&server,lean);

		if(err!=SOCKET_ERROR)

		{

			err=recvfrom(socket1,buffer,sizeof(buffer),0,(sockaddr *)&server,&lean);

			if(err!=SOCKET_ERROR)

			{

				printf("receive from server:%s\n",buffer);

			}

		}

	}

	closesocket(socket1);

}

BOOL InitWinsock()

{

	int Error;

	WORD Version;

	WSADATA Wsa;

	Version=MAKEWORD(2,2);

	Error=WSAStartup(Version,&Wsa);

	if(Error!=0)

	{

		return FALSE;

	}

	else

	{

		if(LOBYTE(Wsa.wVersion)!=2 || HIBYTE(Wsa.wHighVersion)!=2)

		{

			WSACleanup();

			return FALSE;

		}

	}

	return TRUE;

}

启动client以及server端，查看执行效果：

程序仍然存在非常大的问题，慢慢改动咯！