subject_19635.htm

来自「一些关于vc的问答」· HTM 代码 · 共 36 行

<p>
序号：19635 发表者：江观 发表日期：2002-10-30 11:23:37
<br>主题：帮忙
<br>内容：<BR>void CHpcComDoc::OnCommRecv() <BR>{<BR>// TODO: Add your command handler code here<BR>char pBuff[100];<BR>int nLength;<BR>CString str;<BR>CEditView *pView;<BR>POSITION firstViewPos;<BR>&nbsp;&nbsp; <BR>&nbsp;&nbsp;firstViewPos=GetFirstViewPosition();<BR>&nbsp;&nbsp;pView=(CEditView *)GetNextView(firstViewPos);<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;if(!m_bConnected)<BR>&nbsp;&nbsp; {<BR>&nbsp;&nbsp;&nbsp;&nbsp; AfxMessageBox(_T("Can't open connection"));<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return;<BR>&nbsp;&nbsp; }<BR>&nbsp;&nbsp;&nbsp;&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;nLength=RecData(pBuff,100);<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;if(nLength==0)<BR>&nbsp;&nbsp;&nbsp;&nbsp;AfxMessageBox(_T("Receiving data fail"));<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;if(nLength)<BR>&nbsp;&nbsp;&nbsp;&nbsp;{<BR>&nbsp;&nbsp;&nbsp;&nbsp;for(int i=0;i&lt;nLength;i++)<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;str=pBuff[0];<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;AfxMessageBox(_T("Receiving data Successfully"));<BR>&nbsp;&nbsp;&nbsp;&nbsp;}<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; strcpy(pBuff,"");<BR><BR>&nbsp;&nbsp;CEdit& edit = (CEdit&)pView-&gt;GetEditCtrl();<BR>&nbsp;&nbsp;nLength=edit.GetWindowTextLength();<BR>&nbsp;&nbsp;edit.SetSel(nLength,nLength); //移动插入光标到正文末尾<BR><BR>&nbsp;&nbsp;//edit.SetSel(-1, 0);<BR>&nbsp;&nbsp;edit.ReplaceSel(str); // 向编辑视图中插入收到的字符<BR>}<BR><BR><BR><BR><BR>DWORD CHpcComDoc::RecData(char *pBuff, DWORD dwDataLength)<BR>{ <BR>DWORD dwBytesRead=0;// 实际接收的字节数<BR>DWORD dwBytesWrite=0;<BR>COMSTAT ComStat;// 定义一个COMSTAT结构<BR>DWORD dwErrorFlags;// 用于返回串行驱动程序的错误值<BR>DWORD dwCommModemStatus;// CE_OVERRUN, CE_RXPARITY, CE_FRAME, CE_TXFULL<BR><BR><BR>&nbsp;&nbsp;ClearCommError(m_hCom,&dwErrorFlags,&ComStat);// 清除通信错误<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp; // Specify a set of events to be monitored for the port.<BR>&nbsp;&nbsp;SetCommMask (m_hCom, EV_RXCHAR);<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;// 等待接收终端握手信号&nbsp;&nbsp;&nbsp;&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;while(1)<BR>&nbsp;&nbsp; {<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; // Wait for an event to occur for the port.<BR>&nbsp;&nbsp;&nbsp;&nbsp;WaitCommEvent (m_hCom, &dwCommModemStatus, 0);<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; // Re-Specify the set of events to be monitored for the port.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <BR>&nbsp;&nbsp;&nbsp;&nbsp;SetCommMask (m_hCom, EV_RXCHAR);<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;if (dwCommModemStatus & EV_RXCHAR) <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{&nbsp;&nbsp; <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ReadFile (m_hCom, pBuff, 1, &dwBytesRead, 0);<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if(dwBytesRead==1)&nbsp;&nbsp;&nbsp;&nbsp; <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;break;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;} <BR>&nbsp;&nbsp;&nbsp;&nbsp;}<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return dwBytesRead;<BR>}<BR><BR>我希望每次调用OnCommRecv() 都能输出当前输入的1个字符<BR>但如果第一次调用，输入123,输出1，可以。第二次调用，输入456，应输出4，却输出2，应该是缓冲区没有清空，请问应该怎麽办？能不能用strcpy(pBuff,"")清？在哪清？请高手帮忙<BR><BR><BR>
<br><a href="javascript:history.go(-1)">返回上页</a><br><a href=http://www.copathway.com/cndevforum/>访问论坛</a></p>
<hr size=1>
<blockquote><p>
回复者：未出手的飞刀 回复日期：2002-10-30 14:19:07
<br>内容：<BR>不是 pBuff 没清吧，<BR>ReadFile (m_hCom, pBuff, 1, &dwBytesRead, 0);不是自动清了吗
<br>
<a href="javascript:history.go(-1)">返回上页</a><br><a href=http://www.copathway.com/cndevforum/>访问论坛</a></p></blockquote>
<hr size=1>
<blockquote><p>
回复者：江观 回复日期：2002-10-30 16:17:21
<br>内容：那请问是那里的原因呢？<BR>
<br>
<a href="javascript:history.go(-1)">返回上页</a><br><a href=http://www.copathway.com/cndevforum/>访问论坛</a></p></blockquote>
<hr size=1>
<blockquote><p>
<font color=red>答案被接受</font><br>回复者：不说 回复日期：2002-10-30 23:50:26
<br>内容：你每次只读一个字节当然没有清空COM口的缓冲区啦，正确的做法应该是：<BR><BR>ClearCommError(m_hIDComDev, &dwErrorFlags, &ComStat);<BR>if (!ComStat.cbInQue) //这里要判断一下读入缓冲区中有没有东西，有东西才读<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return (0);<BR>&nbsp;&nbsp;&nbsp;&nbsp;<BR>dwBytesRead =(DWORD) ComStat.cbInQue;//把缓冲区里的东西全读出来，否则下次读的时候读进来的就是上次剩下的。<BR><BR>bReadStatus = ReadFile(m_hIDComDev, buffer, dwBytesRead, &dwBytesRead, &m_OverlappedRead);<BR><BR>读进来以后再对缓冲区进行操作，把不需要的东西扔掉。<BR>&nbsp;&nbsp;&nbsp;&nbsp;
<br>
<a href="javascript:history.go(-1)">返回上页</a><br><a href=http://www.copathway.com/cndevforum/>访问论坛</a></p></blockquote>
<hr size=1>
<blockquote><p>
回复者：江观 回复日期：2002-10-31 11:34:51
<br>内容：谢谢你@不说@，调试成功了。再问，如果我想输出第2个字符的话，改动str=pBuff[1]就可以了吧？
<br>
<a href="javascript:history.go(-1)">返回上页</a><br><a href=http://www.copathway.com/cndevforum/>访问论坛</a></p></blockquote>
<hr size=1>
<blockquote><p>
回复者：不说 回复日期：2002-10-31 11:47:33
<br>内容：yes，反正记得读一次处理一次就成了
<br>
<a href="javascript:history.go(-1)">返回上页</a><br><a href=http://www.copathway.com/cndevforum/>访问论坛</a></p></blockquote>