📄 function.fseek.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 on a file pointer</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.fscanf.html">fscanf</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.fstat.html">fstat</a></div> <div class="up"><a href="ref.filesystem.html">Filesystem Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="function.fseek" class="refentry"> <div class="refnamediv"> <h1 class="refname">fseek</h1> <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">fseek</span> — <span class="dc-title">Seeks on a file pointer</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>fseek</b></b></span> ( <span class="methodparam"><span class="type">resource</span> <tt class="parameter">$handle</tt></span> , <span class="methodparam"><span class="type">int</span> <tt class="parameter">$offset</tt></span> [, <span class="methodparam"><span class="type">int</span> <tt class="parameter">$whence</tt></span> ] )</div> <p class="para rdfs-comment"> Sets the file position indicator for the file referenced by <i><tt class="parameter">handle</tt></i>. The new position, measured in bytes from the beginning of the file, is obtained by adding <i><tt class="parameter">offset</tt></i> to the position specified by <i><tt class="parameter">whence</tt></i>. </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><i><tt class="parameter">handle</tt></i></span> <dd> <p class="para">A file system pointer <a href="language.types.resource.html" class="type resource">resource</a>that is typically created using <a href="function.fopen.html" class="function">fopen()</a>.</p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">offset</tt></i></span> <dd> <p class="para"> The offset. </p> <p class="para"> To move to a position before the end-of-file, you need to pass a negative value in <i><tt class="parameter">offset</tt></i>. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">whence</tt></i></span> <dd> <p class="para"> <i><tt class="parameter">whence</tt></i> values are: <ul class="simplelist"> <li class="member"><b><tt>SEEK_SET</tt></b> - Set position equal to <i><tt class="parameter">offset</tt></i> bytes.</li> <li class="member"><b><tt>SEEK_CUR</tt></b> - Set position to current location plus <i><tt class="parameter">offset</tt></i>.</li> <li class="member"><b><tt>SEEK_END</tt></b> - Set position to end-of-file plus <i><tt class="parameter">offset</tt></i>.</li> </ul> </p> <p class="para"> If <i><tt class="parameter">whence</tt></i> is not specified, it is assumed to be <b><tt>SEEK_SET</tt></b>. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Upon success, returns 0; otherwise, returns -1. Note that seeking past EOF is not considered an error. </p> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 <b>fseek()</b> example</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /><br />$fp </span><span style="color: #007700">= </span><span style="color: #0000BB">fopen</span><span style="color: #007700">(</span><span style="color: #DD0000">'somefile.txt'</span><span style="color: #007700">, </span><span style="color: #DD0000">'r'</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// read some data<br /></span><span style="color: #0000BB">$data </span><span style="color: #007700">= </span><span style="color: #0000BB">fgets</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #0000BB">4096</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// move back to the beginning of the file<br />// same as rewind($fp);<br /></span><span style="color: #0000BB">fseek</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </p> </div> <div class="refsect1 notes"> <h3 class="title">Notes</h3> <blockquote><p><b class="note">Note</b>: If you have opened the file in append ("a" or "a+") mode, any data you write to the file will always be appended, regardless of the file position. <br /> </p></blockquote> <blockquote><p><b class="note">Note</b>: May not be used on file pointers returned by <a href="function.fopen.html" class="function">fopen()</a> if they use the "http://" or "ftp://" formats. <b>fseek()</b> gives also undefined results for append-only streams (opened with "a" flag). <br /> </p></blockquote> </div> <div class="refsect1 seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"><a href="function.ftell.html" class="function" rel="rdfs-seeAlso">ftell()</a></li> <li class="member"><a href="function.rewind.html" class="function" rel="rdfs-seeAlso">rewind()</a></li> </ul> </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.fscanf.html">fscanf</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.fstat.html">fstat</a></div> <div class="up"><a href="ref.filesystem.html">Filesystem 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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