Untitled

<?php
$f = array(
0=>1,
1=>1,
2=>2,
3=>6,
4=>24,
5=>120,
6=>720,
7=>5040,
8=>40320,
9=>362990);
var_dump(array_keys($f));
var_dump(array_values($f));
var_dump(str_split(12345));
var_dump(str_replace(array_keys($f), array_values($f), str_split("12345")));
?>
Output:
array(10) {
  [0]=>
  int(0)
  [1]=>
  int(1)
  [2]=>
  int(2)
  [3]=>
  int(3)
  [4]=>
  int(4)
  [5]=>
  int(5)
  [6]=>
  int(6)
  [7]=>
  int(7)
  [8]=>
  int(8)
  [9]=>
  int(9)
}
array(10) {
  [0]=>
  int(1)
  [1]=>
  int(1)
  [2]=>
  int(2)
  [3]=>
  int(6)
  [4]=>
  int(24)
  [5]=>
  int(120)
  [6]=>
  int(720)
  [7]=>
  int(5040)
  [8]=>
  int(40320)
  [9]=>
  int(362990)
}
array(5) {
  [0]=>
  string(1) "1"
  [1]=>
  string(1) "2"
  [2]=>
  string(1) "3"
  [3]=>
  string(1) "4"
  [4]=>
  string(1) "5"
}
array(5) {
  [0]=>
  string(1) "1"
  [1]=>
  string(1) "2"
  [2]=>
  string(6) "504020" // WTF?
  [3]=>
  string(2) "24"
  [4]=>
  string(3) "120"
}