A "slug" is a url that is generated given some text (for example, a webpage title) so that the url for a given item is readable for humans.

For example, the url at a store for blue pens, domain/?id=123 could use a slug to make it human readable, domain/blue-pens?id=123 or simply domain/blue-pens

Implementations

Java

package util;

import java.text.Normalizer;
import java.text.Normalizer.Form;
import java.util.Locale;
import java.util.regex.Pattern;

public class Slug {

  private static final Pattern NONLATIN = Pattern.compile("[^\\w-]");
  private static final Pattern WHITESPACE = Pattern.compile("[\\s]");

  public String makeSlug(String input) {
    String nowhitespace = WHITESPACE.matcher(input).replaceAll("-");
    String normalized = Normalizer.normalize(nowhitespace, Form.NFD);
    String slug = NONLATIN.matcher(normalized).replaceAll("");
    return slug.toLowerCase(Locale.ENGLISH);
  }
}

Perl

my $input = 'In C#: How do I add "Quotes" around string in a comma delimited list of strings?';

my $length = 20;
$input =~ s/[^a-z0-9]+/-/gi;
$input =~ s/^(.{1,$length}).*/\L$1/;

print "$input\n";

Ruby

def seo_friendly(str)
  str.strip.downcase.gsub /\W+/, '-'
end

Python

Using django.

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

C#

private string ToSeoFriendly(string title, int maxLength) {
    var match = Regex.Match(title.ToLower(), "[\\w]+");
    StringBuilder result = new StringBuilder("");
    bool maxLengthHit = false;
    while (match.Success && !maxLengthHit) {
        if (result.Length + match.Value.Length <= maxLength) {
            result.Append(match.Value + "-");
        } else {
            maxLengthHit = true;
            // Handle a situation where there is only one word and it is greater than the max length.
            if (result.Length == 0) result.Append(match.Value.Substring(0, maxLength));
        }
        match = match.NextMatch();
    }
    // Remove trailing '-'
    if (result[result.Length - 1] == '-') result.Remove(result.Length - 1, 1);
    return result.ToString();
}

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;
}