(PHP 5 >= 5.2.0)
mb_stripos — Finds position of first occurrence of a string within another, case insensitive
$haystack
   , string $needle
   [, int $offset = 0
   [, string $encoding = mb_internal_encoding()
  ]] )
   mb_stripos() returns the numeric position of
   the first occurrence of needle in the
   haystack string.
   Unlike mb_strpos(), 
   mb_stripos() is case-insensitive.
   If needle is not found, it returns FALSE.
  
haystack
       The string from which to get the position of the first occurrence
       of needle
      
needle
       The string to find in haystack
      
offset
       The position in haystack
       to start searching
      
encodingCharacter encoding name to use. If it is omitted, internal character encoding is used.
   Return the numeric position of the first occurrence of
   needle in the haystack
   string, or FALSE if needle is not found.