how to decrease 5 month from the today date in codeigniter php
<p>i have today date like <code>2013-03-09 02:12:36</code> i want to get the output like <code>2012-10-09 02:12:36</code> (5 month ago time)</p>

<p>I am getting today with code
             <code>
              $datestring = "%Y-%m-%d: %d:%h:%i";
              $time = time(); 
              $today=mdate($datestring, $time);//gives me</code>2013-03-09 02:12:36``</p>

<p>What i want is 
              <code>$sixmonth= $today  - 6 month//how to get this output</code></p>

<p>Please help me.                 </p>
