Change string into lowercase slug

_slug-text.php

<?php
/**
 * Change string into lowercase slug
 * 
 * @param 	$string 	Any string
 * @return 	$string 	Converted string into slug
 */
function slug($string) {
    # Lower case everything
    $string = strtolower($string);
    # Make alphanumeric (removes all other characters)
    $string = preg_replace("/[^a-z0-9_\s-]/", "", $string);
    # Clean up multiple dashes or whitespaces
    $string = preg_replace("/[\s-]+/", " ", $string);
    # Convert whitespaces and underscore to dash
    $string = preg_replace("/[\s_]/", "-", $string);
    return $string;
}