UTF8 encode array/object structure in PHP

gistfile1.php

<?php
function utf8_encode_deep(&$input) {
	if (is_string($input)) {
		$input = utf8_encode($input);
	} else if (is_array($input)) {
		foreach ($input as &$value) {
			utf8_encode_deep($value);
		}
		
		unset($value);
	} else if (is_object($input)) {
		$vars = array_keys(get_object_vars($input));
		
		foreach ($vars as $var) {
			utf8_encode_deep($input->$var);
		}
	}
}
?>

Thanks for the idea, tipochka, but it still does not work. Here is an example for non-working code, since I got no idea how to change the different -Elements. In the follwing example for the line "foreach ($input as $k=>$val)" $k is twice 'bar'. That occurs errors. And foreach by reference is not possible here (Fatal-Error).

$xml_string = "<?xml version='1.0'?><foo><bar><bar_string><![CDATA[example1ÄÖÜ]]></bar_string></bar><bar><bar_string><![CDATA[example2ÄÖÜ]]></bar_string></bar></foo>"

//must be UTF8 to work fine with this function.
$xml = simplexml_load_string($xml_string);

//Now I cannot decode.
$xml_utf8_decoded = Tools::utf8_code_deep($xml, FALSE);

thanks :)