- print_r: documentation ( source)
- array_keys: documentation ( source)
<?php
$array = array(0 => 200, '730404' => 89730 ,'730205' => 1000 ,'730100' => 1000 ,'730601' => 2184);
$key='730404';
$keys = array_keys($array,$key,0);
print_r($keys);
?>