Description:
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---
From manual page: http://www.php.net/function.array-search%23Changelog
---
array_search gives the result of false when nothing will be found , that is equal to  index 0, why not -1.
-1 means like in javascript , nothing is found.
0 would than be a correkt index found number.



Test script:
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<?php
$array = array(0 => 'blau', 1 => 'rot', 2 => 'grün', 3 => 'rot');

$key = array_search('grün', $array);  // $key = 2;
$key = array_search('rot', $array);   // $key = 1;
$key = array_search('yello', $array);   // $key = 0; 0 is equal to false

$key = isset( $array[$key] ) ? $key : -1 ; // this solve that 0/false to -1

?>