array_filter problem with 0's

I have a string $num = "012 4290-2008"; I made it an array with I tried to get the integers from the string like this. $value = str_split($num); $value_new = array_filter($value, "return_int"); function return_int($value){ if(ctype_digit($value)){ echo $value; return $value; } } The echo prints out all the digits including the 0. But the $value_new are missing the 0's. I would appreciate it if some one can point me in the right direction Thanks in advance Chris