subject_14793.htm

一些关于vc的问答

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序号：14793 发表者：陈少波 发表日期：2002-09-11 15:32:55
<br>主题：如何接受广播的UDP包呢？
<br>内容：如何接受广播的UDP包呢？
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回复者：daibo 回复日期：2002-09-11 15:35:07
<br>内容：邦定地址为广播地址，只要和发送方的端口一致，就可以接收了
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回复者：陈少波 回复日期：2002-09-11 15:45:13
<br>内容：看如下代码能实现吗？我在接受的时候发生错误！为什么呢？<BR>创建套接字：&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int Sockfd;<BR>&nbsp;&nbsp;&nbsp;&nbsp;sockaddr_in hostip;<BR>&nbsp;&nbsp;&nbsp;&nbsp;Sockfd=socket(AF_INET,SOCK_DGRAM,0);<BR>&nbsp;&nbsp;&nbsp;&nbsp;if(Sockfd==INVALID_SOCKET){<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;AfxMessageBox("创建套接口失败!");<BR>&nbsp;&nbsp;&nbsp;&nbsp;}<BR>&nbsp;&nbsp;&nbsp;&nbsp;hostip.sin_family=AF_INET;<BR>&nbsp;&nbsp;&nbsp;&nbsp;hostip.sin_addr.s_addr=INADDR_ANY;<BR>&nbsp;&nbsp;&nbsp;&nbsp;hostip.sin_port=htons(12180);<BR>&nbsp;&nbsp;&nbsp;&nbsp;bool optval=TRUE;<BR>&nbsp;&nbsp;&nbsp;&nbsp;setsockopt(Sockfd,SOL_SOCKET,SO_REUSEADDR,(char FAR *)&optval,sizeof(optval));<BR>&nbsp;&nbsp;&nbsp;&nbsp;if(bind(Sockfd,(struct sockaddr *)&hostip,sizeof(hostip))==SOCKET_ERROR){<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;AfxMessageBox("主机绑定错误!");<BR>&nbsp;&nbsp;&nbsp;&nbsp;}<BR>&nbsp;&nbsp;&nbsp;&nbsp;if(setsockopt(Sockfd,SOL_SOCKET,SO_BROADCAST,(char FAR *)&optval,sizeof(optval))==SOCKET_ERROR){<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;AfxMessageBox("广播通信设置产生错误!");<BR>&nbsp;&nbsp;&nbsp;&nbsp;}<BR>发送消息:<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; sockaddr_in destip;<BR>&nbsp;&nbsp;&nbsp;&nbsp;int state;<BR>&nbsp;&nbsp;&nbsp;&nbsp;destip.sin_family=AF_INET;<BR>&nbsp;&nbsp;&nbsp;&nbsp;destip.sin_addr.s_addr=INADDR_BROADCAST;<BR>&nbsp;&nbsp;&nbsp;&nbsp;destip.sin_port=htons(12181);<BR>&nbsp;&nbsp;&nbsp;&nbsp;if(state=sendto(sock,(char *)buffer,buffersize,0,(struct sockaddr *)&destip,sizeof(destip))==SOCKET_ERROR){<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;AfxMessageBox("数据发送失败");<BR>&nbsp;&nbsp;&nbsp;&nbsp;}<BR>接收消息：<BR>&nbsp;&nbsp;&nbsp;&nbsp;int state;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; sockaddr *sa;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int salen;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; char buffer[15];<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int buffersize;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; buffersize=15;<BR>&nbsp;&nbsp;&nbsp;&nbsp;if(state=recvfrom(sock,(char *)buffer,buffersize,0,sa,&salen)==SOCKET_ERROR){<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;AfxMessageBox("数据接收失败");<BR>&nbsp;&nbsp;&nbsp;&nbsp;}<BR>关闭套接字：<BR>&nbsp;&nbsp;&nbsp;&nbsp;closesocket(sock);<BR>
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<font color=red>答案被接受</font><br>回复者：daibo 回复日期：2002-09-13 14:46:00
<br>内容：接收端也必须初始化SOCKET和地址，端口，才能接收
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