ibm-information-center/dist/eclipse/plugins/i5OS.ic.apis_5.4.0.1/fclear64.htm

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<title>fclear64()--Write (Binary Zeros) to Descriptor (Large File Enabled)</title>
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<h2>fclear64()---Write (Binary Zeros) to Descriptor (Large File Enabled)</h2>
<div class="box" style="width: 60%;">
<br>
&nbsp;&nbsp;Syntax<br>
<pre>
#include &lt;unistd.h&gt;
off64_t fclear
(int <em>file_descriptor</em>, off64_t <em>nbyte</em>);
</pre>
<br>
&nbsp;&nbsp;Service Program Name: QP0LLIB1<br>
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&nbsp;&nbsp;Default Public Authority: *USE<br>
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&nbsp;&nbsp;Threadsafe: Conditional; see <a href="#USAGE_NOTES">Usage
Notes</a>.<br>
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<p>The <strong>fclear64()</strong> function writes <em>nbyte</em> bytes
of binary zeros to the file associated with the <em>file_descriptor</em>.
If <em>nbyte</em> is zero,
<strong>fclear64()</strong> simply returns a value of zero without attempting any
other action.</p>
<p><strong>fclear64()</strong> is enabled for large files. It is capable of operating
on files larger than 2GB minus 1 bytes and is capable of clearing up to the system
allowed maximum file size bytes as long as the file exists in Root, QOpenSys,
and UDFS file systems and has been opened by either of the following:</p>
<ul>
<li>Using the <strong>open64()</strong> function (see
<a href="open64.htm">open64()--Open File (Large File Enabled)</a>).
</li>
<li>Using the <strong>open()</strong> function (see
<a href="open.htm">open()--Open File</a>) with the O_LARGEFILE flag
set in the oflag parameter.
</li>
</ul>
<p>For additional information about parameters, authorities, error conditions,
and examples, see <a href="fclear.htm">fclear()--Write (Binary Zeros) to Descriptor</a>.</p>
<h3>Usage Notes</h3>
<ol type="1">
<li>When you develop in C-based languages, the prototypes for the 64-bit APIs
are normally hidden. To use the <b>fclear64()</b> API, you must compile
the source with the _LARGE_FILE_API macro defined.</li>
<li>All of the usage notes for <b>fclear()</b> apply to <b>
fclear64()</b>. See <em>Usage Notes</em> in the <b>fclear()</b>
API.</li>
</ol>
<br>
<hr>
<p>API introduced: V5R3</p>
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