PHP Date not calculating properly
<p>I have this code, and it prints out as '01/01/1970'</p>

<pre><code>$dob = mktime(0, 0, 0, date("m"), date("d")-1, date("y")-18);
echo "DOB is ".date("d/m/y", $dob); 
</code></pre>

<p>Why is the year not 18 years less than today?</p>
