PHPグリニッジ時間相関関数

/**
 *               
 *
 * @return  integer
 */
function gmtime()
{
    return (time() - date('Z'));
}

/**
 *  GMT                
 *
 * @param  string       $format
 * @param  integer      $time               GMT    
 *
 * @return  string
 */

function local_date($format, $time = NULL)
{
    $timezone = isset($_SESSION['timezone']) ? $_SESSION['timezone'] : '+8';

    if ($time === NULL)
    {
        $time = gmtime();
    }
    elseif ($time <= 0)
    {
        return '';
    }

    $time += ($timezone * 3600);

    return date($format, $time);
}