utility.php

<?php
    // Function for transliteration
    function transliterate($string) {
        $transliteration = array(
            'а' => 'a', 'б' => 'b', 'в' => 'v', 'г' => 'g', 'д' => 'd',
            'е' => 'e', 'ё' => 'yo', 'ж' => 'zh', 'з' => 'z', 'и' => 'i',
            'й' => 'y', 'к' => 'k', 'л' => 'l', 'м' => 'm', 'н' => 'n',
            'о' => 'o', 'п' => 'p', 'р' => 'r', 'с' => 's', 'т' => 't',
            'у' => 'u', 'ф' => 'f', 'х' => 'h', 'ц' => 'ts', 'ч' => 'ch',
            'ш' => 'sh', 'щ' => 'sch', 'ъ' => '', 'ы' => 'y', 'ь' => '',
            'э' => 'e', 'ю' => 'yu', 'я' => 'ya', 'А' => 'A', 'Б' => 'B',
            'В' => 'V', 'Г' => 'G', 'Д' => 'D', 'Е' => 'E', 'Ё' => 'Yo',
            'Ж' => 'Zh', 'З' => 'Z', 'И' => 'I', 'Й' => 'Y', 'К' => 'K',
            'Л' => 'L', 'М' => 'M', 'Н' => 'N', 'О' => 'O', 'П' => 'P',
            'Р' => 'R', 'С' => 'S', 'Т' => 'T', 'У' => 'U', 'Ф' => 'F',
            'Х' => 'H', 'Ц' => 'Ts', 'Ч' => 'Ch', 'Ш' => 'Sh', 'Щ' => 'Sch',
            'Ъ' => '', 'Ы' => 'Y', 'Ь' => '', 'Э' => 'E', 'Ю' => 'Yu',
            'Я' => 'Ya'
        );
        $string = strtr($string, $transliteration);
        $string = preg_replace('/[^a-zA-Z0-9\-]/', '-', $string);
        $string = preg_replace('/-+/', '-', $string);
        $string = trim($string, '-');
        return $string;
    }

    function dataFilter($string = "", $db_link = null) {
        $string = strip_tags($string);
        $string = stripslashes($string);
        $string = htmlspecialchars($string);
        $string = trim($string);
        if(isset($db_link) && $db_link != null) {
            $string = $db_link->real_escape_string($string);
        }
        return $string;
    }