How can I create a SEO friendly dash-delimited url from a string?

Question

Take a string such as:

In C#: How do I add \"Quotes\" around string in a comma delimited list of strings?

and convert it to:

Answer 1

I would follow these steps:

1. convert string to lower case
2. replace unwanted characters by hyphens
3. replace multiple hyphens by one hyphen (not necessary as the preg_replace() function call already prevents multiple hyphens)
4. remove hypens at the begin and end if necessary
5. trim if needed from the last hyphen before position x to the end

So, all together in a function (PHP):

function generateUrlSlug($string, $maxlen=0)
{
    $string = trim(preg_replace('/[^a-z0-9]+/', '-', strtolower($string)), '-');
    if ($maxlen && strlen($string) > $maxlen) {
        $string = substr($string, 0, $maxlen);
        $pos = strrpos($string, '-');
        if ($pos > 0) {
            $string = substr($string, 0, $pos);
        }
    }
    return $string;
}