<?php
$dates = array('31/05/1997','14/07/1996','31/03/1999','02/03/1999');

for ($i = 0; $i < count($dates); $i++) {
   $date = $dates[$i];

   $yr = substr($date,6,4);
   $mo = substr($date,3,2);
   $dy = substr($date,0,2);
   $ndate = "$yr-$mo-$dy";

   // $ndate = date("Y-m-d",strtotime($date));
   echo("$date  ->  $ndate\n");
}

?>