o one (except
if a <code>NULL</code> pointer was passed).</p>
</dd>
<dt class="hdlist1"><code>OPT_NUMBER_CALLBACK(&amp;var, description, func_ptr)</code></dt>
<dd>
<p>Recognize numerical options like -123 and feed the integer as
if it was an argument to the function given by <code>func_ptr</code>.
The result will be put into <code>var</code>.  There can be only one such
option definition.  It cannot be negated and it takes no
arguments.  Short options that happen to be digits take
precedence over it.</p>
</