man/tip/nng_aio_count.3.html


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---
version: tip
layout: manpage_v2
title: nng_aio_count(3)
---
<h1>nng_aio_count(3)</h1>
<div class="sect1">
<h2 id="_name">NAME</h2>
<div class="sectionbody">
<div class="paragraph">
<p>nng_aio_count - return number of bytes transferred</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_synopsis">SYNOPSIS</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="c"><span></span><span class="tok-cp">#include</span><span class="tok-w"> </span><span class="tok-cpf">&lt;nng/nng.h&gt;</span>

<span class="tok-kt">size_t</span><span class="tok-w"> </span><span class="tok-nf">nng_aio_count</span><span class="tok-p">(</span><span class="tok-n">nng_aio</span><span class="tok-w"> </span><span class="tok-o">*</span><span class="tok-n">aio</span><span class="tok-p">);</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_description">DESCRIPTION</h2>
<div class="sectionbody">
<div class="paragraph">
<p>The <code>nng_aio_count()</code> returns the number of bytes transferred by the
asynchronous operation associated with the handle <em>aio</em>.</p>
</div>
<div class="paragraph">
<p>Some asynchronous operations do not provide meaningful data for this
function; for example operations that establish connections do not
transfer user data (they may transfer protocol data though)&#8201;&#8212;&#8201;in this case
this function will generally return zero.</p>
</div>
<div class="paragraph">
<p>This function is most useful when used with operations that make use of
of a scatter/gather vector (set by <a href="nng_aio_set_iov.3.html"><code>nng_aio_set_iov()</code></a>).</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
The return value from this function is undefined if the operation
has not completed yet.
Either call this from the handle&#8217;s completion callback,
or after waiting for the operation to complete with
<a href="nng_aio_wait.3.html"><code>nng_aio_wait()</code></a>.
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_return_values">RETURN VALUES</h2>
<div class="sectionbody">
<div class="paragraph">
<p>The number of bytes transferred by the operation.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_errors">ERRORS</h2>
<div class="sectionbody">
<div class="paragraph">
<p>None.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_see_also">SEE ALSO</h2>
<div class="sectionbody">
<div class="paragraph text-left">
<p><a href="nng_aio_alloc.3.html">nng_aio_alloc(3)</a>,
<a href="nng_aio_result.3.html">nng_aio_result(3)</a>,
<a href="nng_aio_set_iov.3.html">nng_aio_set_iov(3)</a>,
<a href="nng_aio_wait.3.html">nng_aio_wait(3)</a>,
<a href="nng_strerror.3.html">nng_strerror(3)</a>,
<a href="nng_aio.5.html">nng_aio(5)</a>,
<a href="nng.7.html">nng(7)</a></p>
</div>
</div>
</div>