<?php
$dateextraite = "2005-04-04";

$newdate = preg_replace("!(\d{4})-(\d{2})-(\d{2})!","\\2/\\3/\\1",$dateextraite);

echo $newdate;
//Affiche 04/04/2005
?>

function dateConverter($date)
{
    return preg_replace("#(\d{2,4})(\D)(\d{2,4})\\2(\d{2,4})#", "$4$2$3$2$1", $date);
}

echo dateConverter("1970-01-01"); // retourne 01-01-1970
echo dateConverter("26/08/2004"); // retourne 2004/08/26
echo dateConverter("79x12x26"); // retourne 26x12x79