(PHP 5)
strripos — Find the position of the last occurrence of a case-insensitive substring in a string
$haystack
   , string $needle
   [, int $offset = 0
  ] )
   Find the numeric position of the last occurrence of
   needle in the haystack string.
  
Unlike the strrpos(), strripos() is case-insensitive.
haystackThe string to search in.
needle
       If needle is not a string, it is converted
       to an integer and applied as the ordinal value of a character.
      
offsetIf specified, search will start this number of characters counted from the beginning of the string. If the value is negative, search will instead start from that many characters from the end of the string, searching backwards.
   Returns the position where the needle exists relative to the beginnning of
   the haystack string (independent of search direction
   or offset).
   Also note that string positions start at 0, and not 1.
  
   Returns FALSE if the needle was not found.
  
This function may
return Boolean FALSE, but may also return a non-Boolean value which
evaluates to FALSE. Please read the section on Booleans for more
information. Use the ===
operator for testing the return value of this
function.
Example #1 A simple strripos() example
<?php
$haystack = 'ababcd';
$needle   = 'aB';
$pos      = strripos($haystack, $needle);
if ($pos === false) {
    echo "Sorry, we did not find ($needle) in ($haystack)";
} else {
    echo "Congratulations!\n";
    echo "We found the last ($needle) in ($haystack) at position ($pos)";
}
?>
The above example will output:
Congratulations! We found the last (aB) in (ababcd) at position (2)