slugify a string

slugify.php

<?php

function slugify($string){
    
  // trim off hyphens on ends of string
  $string = trim($string, '-');
 
  // replace all non-standard characters or numbers
  $string = preg_replace('~[^\\pL\d]+~u', '-', $string);
	
	// transliterate
	if(function_exists('transliterator_transliterate')){
	    $string = transliterator_transliterate('Any-Latin; Latin-ASCII; Lower()', $string);
	}
	elseif(function_exists('iconv')){
		$string = iconv('UTF-8', 'ISO-8859-1//TRANSLIT', $string);
	}
	
	// convert string to lowercase
	$string = strtolower($string);
	
	// remove unwanted characters
	$string = preg_replace('~[^-\w]+~', '', $string);
	
	// check if string is empty
	if (empty($string)){
		return 'n-a';
	}
	
	return $string;
}

$string = "this ^string (contains) #special cha-racters! ümlaut 1234-";

print(slugify($string));