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<title>Seeks to pos on fd from whence</title>
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<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" id="refsect1-function.dio-seek-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">int</span> <span class="methodname"><strong>dio_seek</strong></span>
( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$fd</code></span>
, <span class="methodparam"><span class="type">int</span> <code class="parameter">$pos</code></span>
[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$whence</code><span class="initializer"> = SEEK_SET</span></span>
] )</div>
<p class="para rdfs-comment">
The function <span class="function"><strong>dio_seek()</strong></span> is used to change the
file position of the given file descriptor.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.dio-seek-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">fd</code></em></span>
<dd>
<p class="para">
The file descriptor returned by <span class="function"><a href="function.dio-open.html" class="function">dio_open()</a></span>.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">pos</code></em></span>
<dd>
<p class="para">
The new position.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">whence</code></em></span>
<dd>
<p class="para">
Specifies how the position <em><code class="parameter">pos</code></em> should be
interpreted:
<ul class="itemizedlist">
<li class="listitem">
<p class="para">
<strong><code>SEEK_SET</code></strong> (default) - specifies that
<em><code class="parameter">pos</code></em> is specified from the beginning of the
file.
</p>
</li>
<li class="listitem">
<p class="para">
<strong><code>SEEK_CUR</code></strong> - Specifies that
<em><code class="parameter">pos</code></em> 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">
<strong><code>SEEK_END</code></strong> - Specifies that
<em><code class="parameter">pos</code></em> 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" id="refsect1-function.dio-seek-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.dio-seek-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-2331">
<p><strong>Example #1 Positioning in a file</strong></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>
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