- mt_rand: documentation ( source)
<?php
function mt_rand_str ($l, $c = '1234567890') {
for ($s = '', $cl = strlen($c)-1, $i = 0; $i < $l; $s .= $c[mt_rand(0, $cl)], ++$i);
return $s;
}
$code = mt_rand_str(10, '0123456789');
echo $code;
?>