function ck_iconv($source_lang, $target_lang, $source_string = '')
{
    static $chs = NULL;
    /* 如果字符串为空或者字符串不需要转换,直接返回 */
    if ($source_lang == $target_lang || $source_string == '' || preg_match("/[�-�]+/", $source_string) == 0) {
        return $source_string;
    }
    if ($chs === NULL) {
        require_once PATH_APPLICATION . '/pm_iconv.class.php';
        $chs = new Chinese();
        $chs->Chinese();
    }
    return strtolower($target_lang) == 'utf-8' ? addslashes(stripslashes($chs->Convert($source_lang, $target_lang, $source_string))) : $chs->Convert($source_lang, $target_lang, $source_string);
}