Something

boda ~ # php-select php php4
boda ~ # php -r 'var_dump(unserialize("a:1:{s:1:\"0\";i:1;}"));'
array(1) {
  [0]=>
  int(1)
}
boda ~ # php-select php php5
boda ~ # php -r 'var_dump(unserialize("a:1:{s:1:\"0\";i:1;}"));'
array(1) {
  ["0"]=>
  int(1)
}