📄 function.dio-seek.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Seeks to pos on fd from whence</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.dio-read.html">dio_read</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.dio-stat.html">dio_stat</a></div> <div class="up"><a href="ref.dio.html">Direct IO Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="function.dio-seek" class="refentry"> <div class="refnamediv"> <h1 class="refname">dio_seek</h1> <p class="verinfo">(PHP 4 >= 4.2.0, PHP 5 <= 5.0.5)</p><p class="refpurpose"><span class="refname">dio_seek</span> — <span class="dc-title">Seeks to pos on fd from whence</span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">int</span> <span class="methodname"><b><b>dio_seek</b></b></span> ( <span class="methodparam"><span class="type">resource</span> <tt class="parameter">$fd</tt></span> , <span class="methodparam"><span class="type">int</span> <tt class="parameter">$pos</tt></span> [, <span class="methodparam"><span class="type">int</span> <tt class="parameter">$whence</tt></span> ] )</div> <p class="para rdfs-comment"> The function <b>dio_seek()</b> is used to change the file position of the given file descriptor. </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><i><tt class="parameter">fd</tt></i></span> <dd> <p class="para"> The file descriptor returned by <a href="function.dio-open.html" class="function">dio_open()</a>. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">pos</tt></i></span> <dd> <p class="para"> The new position. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">whence</tt></i></span> <dd> <p class="para"> Specifies how the position <i><tt class="parameter">pos</tt></i> should be interpreted: <ul class="itemizedlist"> <li class="listitem"> <p class="para"> <b><tt>SEEK_SET</tt></b> (default) - specifies that <i><tt class="parameter">pos</tt></i> is specified from the beginning of the file. </p> </li> <li class="listitem"> <p class="para"> <b><tt>SEEK_CUR</tt></b> - Specifies that <i><tt class="parameter">pos</tt></i> is a count of characters from the current file position. This count may be positive or negative. </p> </li> <li class="listitem"> <p class="para"> <b><tt>SEEK_END</tt></b> - Specifies that <i><tt class="parameter">pos</tt></i> is a count of characters from the end of the file. A negative count specifies a position within the current extent of the file; a positive count specifies a position past the current end. If you set the position past the current end, and actually write data, you will extend the file with zeros up to that position. </p> </li> </ul> </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> </p> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 Positioning in a file</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /><br />$fd </span><span style="color: #007700">= </span><span style="color: #0000BB">dio_open</span><span style="color: #007700">(</span><span style="color: #DD0000">'/dev/ttyS0'</span><span style="color: #007700">, </span><span style="color: #0000BB">O_RDWR</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">dio_seek</span><span style="color: #007700">(</span><span style="color: #0000BB">$fd</span><span style="color: #007700">, </span><span style="color: #0000BB">10</span><span style="color: #007700">, </span><span style="color: #0000BB">SEEK_SET</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">// position is now at 10 characters from the start of the file<br /><br /></span><span style="color: #0000BB">dio_seek</span><span style="color: #007700">(</span><span style="color: #0000BB">$fd</span><span style="color: #007700">, -</span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #0000BB">SEEK_CUR</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">// position is now at 8 characters from the start of the file<br /><br /></span><span style="color: #0000BB">dio_seek</span><span style="color: #007700">(</span><span style="color: #0000BB">$fd</span><span style="color: #007700">, -</span><span style="color: #0000BB">5</span><span style="color: #007700">, </span><span style="color: #0000BB">SEEK_END</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">// position is now at 5 characters from the end of the file<br /><br /></span><span style="color: #0000BB">dio_seek</span><span style="color: #007700">(</span><span style="color: #0000BB">$fd</span><span style="color: #007700">, </span><span style="color: #0000BB">10</span><span style="color: #007700">, </span><span style="color: #0000BB">SEEK_END</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">// position is now at 10 characters past the end of the file. <br />// The 10 characters between the end of the file and the current<br />// position are filled with zeros.<br /><br /></span><span style="color: #0000BB">dio_close</span><span style="color: #007700">(</span><span style="color: #0000BB">$fd</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.dio-read.html">dio_read</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.dio-stat.html">dio_stat</a></div> <div class="up"><a href="ref.dio.html">Direct IO Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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