一个简单的以太网广播收发例子

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收

#include<stdlib.h>

#include<iostream.h>

#include<conio.h>

#include<stdio.h>

#include<winsock2.h>

#include<windows.h>

#pragma comment(lib,"ws2_32.lib")

void main(void)

{

 SOCKET s;

 sockaddr_in from,a;

 WSADATA wsdata;

 BOOL optval;

 //启动SOCKET库，版本为2.0

 WSAStartup(0x0202,&wsdata);

 optval=TRUE;

 //然后赋值给两个地址，一个用来绑定套接字，一个用来从网络上的广播地址接收消息；

 a.sin_family=AF_INET;

 a.sin_addr.s_addr=0;

 a.sin_port=htons(5050);

 from.sin_family=AF_INET;

 from.sin_addr.s_addr=INADDR_BROADCAST;

 from.sin_port=htons(5050);

 int fromlength=sizeof(SOCKADDR);

 //用UDP初始化套接字

 s=socket(AF_INET,SOCK_DGRAM,0);

   //设置该套接字为广播类型，

 setsockopt(s,SOL_SOCKET,SO_BROADCAST,(char FAR *)&optval,sizeof(optval));

 bind(s,(sockaddr *)&a,sizeof(sockaddr_in));

 char buf[256];

 while(1)

 {//从广播地址接收消息，注意用来绑定的地址和接收消息的地址是不一样的

  recvfrom(s,buf,256,0,(struct sockaddr FAR *)&from,(int FAR *)&fromlength);

  Sleep(2000);

  printf("%s/n",buf);

  ZeroMemory(buf,256);

 }

}

发

#include<stdlib.h>

#include<iostream.h>

#include<stdio.h>

#include<conio.h>

#include<winsock2.h>

#include<windows.h>

#pragma comment(lib,"ws2_32.lib")

main()

{

 SOCKET s;

 sockaddr_in addrto;

 WSADATA wsdata;

 BOOL bsocket;

 char *smsg="this is a test";

 //启动SOCKET库，版本为2.0

 WSAStartup(0x0202,&wsdata);

 s=WSASocket(AF_INET,SOCK_DGRAM,0,NULL,0,WSA_FLAG_OVERLAPPED);

 bsocket=TRUE;

    //然后赋值给地址，用来从网络上的广播地址接收消息；

 addrto.sin_family=AF_INET;

    addrto.sin_addr.s_addr=INADDR_BROADCAST;

 addrto.sin_port=htons(5050);

 bool opt=true;

 //设置该套接字为广播类型，

 setsockopt(s,SOL_SOCKET,SO_BROADCAST,(char FAR *)&opt,sizeof(opt));

 int nlen=sizeof(addrto);

 while(1)

 {

  Sleep(1000);

  //从广播地址发送消息

  int ret=sendto(s,smsg,256,0,(sockaddr*)&addrto,nlen);

  if(ret==SOCKET_ERROR)

   cout<<WSAGetLastError()<<endl;

  else

  {  

   printf("ok"); 

  }

 }

}