- print_r: documentation ( source)
<?php
$options['key'][] = 'testkey1';
$options['value'][] = 'testvalue1';
$options['key'][] = 'testkey2';
$options['value'][] = 'testvalue2';
$options['key'][] = 'testkey3';
$options['value'][] = 'testvalue3';
print_r($options);