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125 lines
6.7 KiB
HTML
125 lines
6.7 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<title>Seeks to pos on fd from whence</title>
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</head>
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<body class="docs"><div id="layout">
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<div id="layout-content"><div id="function.dio-seek" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">dio_seek</h1>
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<p class="verinfo">(PHP 4 >= 4.2.0, PHP 5 < 5.1.0)</p><p class="refpurpose"><span class="refname">dio_seek</span> — <span class="dc-title">Seeks to pos on fd from whence</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.dio-seek-description">
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<h3 class="title">说明</h3>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>dio_seek</strong></span>
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( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$fd</code></span>
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, <span class="methodparam"><span class="type">int</span> <code class="parameter">$pos</code></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$whence</code><span class="initializer"> = SEEK_SET</span></span>
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] ) : <span class="type">int</span></div>
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<p class="para rdfs-comment">
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The function <span class="function"><strong>dio_seek()</strong></span> is used to change the
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file position of the given file descriptor.
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.dio-seek-parameters">
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<h3 class="title">参数</h3>
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<p class="para">
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<dl>
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<dt>
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<code class="parameter">fd</code></dt>
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<dd>
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<p class="para">
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The file descriptor returned by <span class="function"><a href="dio_open.html" class="function">dio_open()</a></span>.
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</p>
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</dd>
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<dt>
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<code class="parameter">pos</code></dt>
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<dd>
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<p class="para">
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The new position.
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</p>
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</dd>
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<dt>
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<code class="parameter">whence</code></dt>
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<dd>
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<p class="para">
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Specifies how the position <code class="parameter">pos</code> should be
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interpreted:
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<ul class="itemizedlist">
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<li class="listitem">
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<p class="para">
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<strong><code>SEEK_SET</code></strong> (default) - specifies that
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<code class="parameter">pos</code> is specified from the beginning of the
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file.
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</p>
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</li>
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<li class="listitem">
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<p class="para">
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<strong><code>SEEK_CUR</code></strong> - Specifies that
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<code class="parameter">pos</code> is a count of characters from the current
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file position. This count may be positive or negative.
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</p>
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</li>
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<li class="listitem">
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<p class="para">
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<strong><code>SEEK_END</code></strong> - Specifies that
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<code class="parameter">pos</code> is a count of characters from the end of
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the file. A negative count specifies a position within the current
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extent of the file; a positive count specifies a position past the
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current end. If you set the position past the current end, and
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actually write data, you will extend the file with zeros up to that
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position.
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</p>
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</li>
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</ul>
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</p>
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</dd>
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</dl>
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</p>
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</div>
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<div class="refsect1 returnvalues" id="refsect1-function.dio-seek-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.dio-seek-examples">
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<h3 class="title">范例</h3>
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<p class="para">
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<div class="example" id="example-2744">
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<p><strong>Example #1 Positioning in a file</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<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>
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</span>
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</pre></div>
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</div>
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</div>
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</p>
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</div>
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</div></div></div></body></html> |