📄 recv.htm
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /><title> UDT Reference</title><link rel="stylesheet" href="udtdoc.css" type="text/css" /></head><body><div class="ref_head"> UDT Reference: Functions</div><h4 class="func_name"><strong>recv</strong></h4><p>The <b>recv</b> method reads certain amount of data into a local memory buffer.</p><div class="code">int recv(<br /> UDTSOCKET <font color="#FFFFFF">u</font>,<br /> char* <font color="#FFFFFF">buf</font>,<br /> int <font color="#FFFFFF">len</font>,<br /> int <font color="#FFFFFF">flags</font><br />);</div><h5>Parameters</h5><dl> <dt><i>u</i></dt> <dd>[in] Descriptor identifying a connected socket.</dd> <dt><em>buf</em></dt> <dd>[out] The buffer used to store incoming data.</dd> <dt><em>len</em></dt> <dd>[in] Length of the buffer.</dd> <dt><em>flags</em></dt> <dd>[in] Ignored. For compatibility only.</dd></dl><h5>Return Value</h5><p>On success, <b>recv</b> returns the actual size of received data. Otherwise UDT::ERROR is returned and specific error information can be retrieved by <a href="error.htm">getlasterror</a>. If UDT_RCVTIMEO is set to a positive value, zero will be returned if no data is received before the timer expires.</p><table width="100%" border="1" cellpadding="2" cellspacing="0" bordercolor="#CCCCCC"> <tr> <td width="17%" class="table_headline"><strong>Error Name</strong></td> <td width="17%" class="table_headline"><strong>Error Code</strong></td> <td width="83%" class="table_headline"><strong>Comment</strong></td> </tr> <tr> <td>ECONNLOST</td> <td>2001</td> <td>connection has been broken and no data left in receiver buffer.</td> </tr> <tr> <td>ENOCONN</td> <td>2002</td> <td><i>u</i> is not connected.</td> </tr> <tr> <td>EINVSOCK</td> <td>5004</td> <td><i>u</i> is not an valid socket.</td> </tr> <tr> <td>EDGRAMILL</td> <td>5010</td> <td>cannot use <i>recv</i> in SOCK_DGRAM mode.</td> </tr> <tr> <td>EASYNCRCV</td> <td>6002</td> <td><i>u</i> is non-blocking (UDT_RCVSYN = false) but no data is available.</td> </tr></table><h5>Description</h5><p>The <strong>recv</strong> method reads certain amount of data from the protocol buffer. If there is not enough data in the buffer, <strong>recv</strong> only reads the available data in the protocol buffer and returns the actual size of data received. However, <strong>recv</strong> will never read more data than the buffer size indicates by <i>len</i>.</p><p>In blocking mode (default), <strong>recv</strong> waits until there is some data received into the receiver buffer. In non-blocking mode, <strong>recv</strong> returns immediately and returns error if no data available.</p><p>If UDT_RCVTIMEO is set and the socket is in blocking mode, <strong>recv</strong> only waits a limited time specified by UDT_RCVTIMEO option. If there is still no data available when the timer expires, zero will be returned. UDT_RCVTIMEO has no effect for non-blocking socket.</p><h5>See Also</h5><p><strong><a href="select.htm">select</a>, <a href="send.htm">send</a>, <a href="sendfile.htm">sendfile</a>, <a href="recvfile.htm">recvfile</a></strong></p><p> </p></body></html>⌨️ 快捷键说明
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