- array_combine: documentation ( source)
- print_r: documentation ( source)
- array_merge: documentation ( source)
- range: documentation ( source)
<?php
$start_options = array( 'null'=>'None'
, '*'=>'*'
);
$end_options = array( '99'=>'99'
);
$options = array_merge( $start_options
, array_combine(range(0,20), range(0,20))
, $end_options
);
print_r($options);