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;
}

Answer 2

This is close to how Stack Overflow generates slugs:

public static string GenerateSlug(string title)
{
    string slug = title.ToLower();
    if (slug.Length > 81)
      slug = slug.Substring(0, 81);
    slug = Regex.Replace(slug, @"[^a-z0-9\-_\./\\ ]+", "");
    slug = Regex.Replace(slug, @"[^a-z0-9]+", "-");

    if (slug[slug.Length - 1] == '-')
      slug = slug.Remove(slug.Length - 1, 1);
    return slug;
}

Answer 3

In python, (if django is installed, even if you are using another framework.)

from django.template.defaultfilters import slugify
slugify("In C#: How do I add "Quotes" around string in a comma delimited list of strings?")

Answer 4

Solution in shell:

echo 'In C#: How do I add "Quotes" around string in a comma delimited list of strings?' | \
    tr A-Z a-z | \
    sed 's/[^a-z0-9]\+/-/g;s/^\(.\{1,20\}\).*/\1/'

Answer 5

A slightly cleaner way of doing this in PHP at least is:

function CleanForUrl($urlPart, $maxLength = null) {
    $url = strtolower(preg_replace(array('/[^a-z0-9\- ]/i', '/[ \-]+/'), array('', '-'), trim($urlPart)));
    if ($maxLength) $url = substr($url, 0, $maxLength);
    return $url;
}

Might as well do the trim() at the start so there is less to process later and the full replacement is done with in the preg_replace().

Thxs to cg for coming up with most of this: What is the best way to clean a string for placement in a URL, like the question name on SO?

Answer 6

A better version:

function Slugify($string)
{
    return strtolower(trim(preg_replace(array('~[^0-9a-z]~i', '~-+~'), '-', $string), '-'));
}