e class="code"><span class="constructor">Not_found</span></code> if <code class="code">c</code> does not occur in <code class="code">s</code>.</p>
</div>
</div>

<pre><span id="VALrindex_opt"><span class="keyword">val</span> rindex_opt</span> : <code class="type">bytes -&gt; char -&gt; int option</code></pre><div class="info ">
<div class="info-desc">
<p><code class="code">rindex_opt&nbsp;s&nbsp;c</code> returns the index of the last occurrence of byte <code class="code">c</code>
    in <code class="code">s