See the manual, it might help you: http://www.php.net/manual/en/function.array-search.php

If what you're trying to do is use increase the key by one, you can do:

function my_array_search($needle, $haystack, $strict=false) {
     $key = array_search($needle, $haystack, $strict);
     if (is_integer($key)) $key++;
     return $key;
}
my_array_search($xml_service_array);

array_search does not start searching at index 1. Try this example:

<?php
$array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red');
$key = array_search('blue', $array);  // $key = 0
?>

Whatever the problem is with your code, it's not that it's first element is index 0.

It's more likely that you're use == instead of === to check the return value. If array_search returns 0, indicating the first element, the following code will not work:

// doesn't work when element 0 is matched!
if (false == array_search(...)) { ... }

Instead, you must check using ===, which compares both value and type

// works, even when element 0 is matched
if (false === array_search(...)) { ... }