I'm sure there's a better way to strip strings from the end of strings.

<?php
/**
 * Strip a string from the end of a string
 *
 * @param string $str      the input string
 * @param string $remove   OPTIONAL string to remove
 *  
 * @return string the modified string
  */
function rstrtrim($str, $remove=null)
{
    $str    = (string)$str;
    $remove = (string)$remove;    
    
    if(empty($remove))
    {
        return rtrim($str);
    }
    
    $len = strlen($remove);
    $offset = strlen($str)-$len;
    while($offset > 0 && $offset == strpos($str, $remove, $offset))
    {
        $str = substr($str, 0, $offset);
        $offset = strlen($str)-$len;
    }
    
    return rtrim($str);    
    
} //End of function rstrtrim($str, $remove=null)

echo rstrtrim('Hello World!!!', '!')   .'<br />'; //"Hello World"
echo rstrtrim('Hello World!!!', '!!')  .'<br />'; //"Hello World!"
echo rstrtrim('Hello World!!!', '!!!') .'<br />'; //"Hello World"
echo rstrtrim('Hello World!!!', '!!!!').'<br />'; //"Hello World!!!"
?>