(PHP 5 >= 5.2.0)
mb_strrichr — Finds the last occurrence of a character in a string within another, case insensitive
$haystack
   , string $needle
   [, bool $part = false
   [, string $encoding = mb_internal_encoding()
  ]] )
   mb_strrichr() finds the last occurrence of
   needle in haystack
   and returns the portion of haystack. Unlike
   mb_strrchr(), mb_strrichr() is
   case-insensitive.
   If needle is not found, it returns FALSE.
  
haystack
       The string from which to get the last occurrence
       of needle
      
needle
       The string to find in haystack
      
part
       Determines which portion of haystack
       this function returns. 
       If set to TRUE, it returns all of haystack
       from the beginning to the last occurrence of needle.
       If set to FALSE, it returns all of haystack
       from the last occurrence of needle to the end,
      
encodingCharacter encoding name to use. If it is omitted, internal character encoding is used.
   Returns the portion of haystack.
   or FALSE if needle is not found.