get_key.php

<?php
/**
 * Return the value for a key in an array or a property in an object.
 * Typical usage:
 * 
 * $object->foo = 'Bar';
 * echo get_key($object, 'foo');
 * 
 * $array['baz'] = 'Bat';
 * echo get_key($array, 'baz');
 * 
 * @param mixed $haystack
 * @param string $needle
 * @param mixed $default_value The value if key could not be found.
 * @return mixed
 */
function get_key ($haystack, $needle, $default_value = '')
{
	if (is_array($haystack)) {
		// We have an array. Find the key.
        return isset($haystack[$needle]) ? $haystack[$needle] : $default_value;
    }
    else {
    	// If it's not an array it must be an object
    	return isset($haystack->$needle) ? $haystack->$needle : $default_value;
    }
}