sanitize.php

/**
 * Function: sanitize
 * Returns a sanitized string, typically for URLs.
 *
 * Parameters:
 *     $string - The string to sanitize.
 *     $lowercase - Force the string to lowercase?
 *     $alnum - If set to *true*, will remove all non-alphanumeric characters.
 */
function sanitize($string, $lowercase = true, $alnum = false) {
    $string = trim(
        strtr(
            strip_tags(
                str_replace(
                    array('`', '^', '\''), null, 
                    iconv(
                        'UTF-8', 
                        'US-ASCII//TRANSLIT//IGNORE', 
                        strtr($string, '\'', ' ')
                    )
                )
            ),
            '~`!@?#$%§^&*()_=+[]{}\\/|;:,"\'<>.', 
            '                                  '
        )
    );
    if ($alnum) $string = preg_replace('/[^a-zA-Z0-9]/', ' ', $string);
    if ($lowercase) $string = strtolower($string);
    return preg_replace('/\s+/', '-', $string);
}