ional second string parameter of &#8216;ipv4&#8217; or &#8216;ipv6&#8217; to specify
an IP format. The default checks for both formats.</p>
</dd></dl>

<dl class="method">
<dt id="CI_Input::user_agent">
<tt class="descname">user_agent</tt><big>(</big><span class="optional">[</span><em>$xss_clean = NULL</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#CI_Input::user_agent" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="no