URL Cleaner PHP Code By using Regular Expression

$string = "URL Cleaner fuction to remove unwanted symbols like $,%,@,! etc.Enjoy it!!!!";
echo encodeUrlParam($string);
function encodeUrlParam( $string )
{
  $string = trim($string);
 
  if ( ctype_digit($string) )
  {
    return $string;
  }
  else
  {
    // replace accented chars
    $accents = '/&([A-Za-z]{1,2})(grave|acute|circ|cedil|uml|lig);/';
    $string_encoded = htmlentities($string,ENT_NOQUOTES,'UTF-8');
 
    $string = preg_replace($accents,'$1',$string_encoded);
 
    // clean out the rest
    $replace = array('([\40])','([^a-zA-Z0-9-])','(-{2,})');
    $with = array('-','','-');
    $string = preg_replace($replace,$with,$string);
  } 
 
  return strtolower($string);
}
?>