UDP实现的广播通信
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//send#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2.0WSAStartup(0x0202,&wsdata);s=WSASocket(AF_INET,SOCK_DGRAM,0,NULL,0,WSA_FLAG_OVERLAPPED);bsocket=TRUE; //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受消息。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。int ret=sendto(s,smsg,256,0,(sockaddr*)&addrto,nlen);if(ret==SOCKET_ERROR)cout<<WSAGetLastError()<<endl;else{printf("ok");}}}//receive#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2.0WSAStartup(0x0202,&wsdata);optval=TRUE;//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受消息。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){ //从广播地址接受消息，注意用绑定的地址和接受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);}}
