function ut_main()
{
    $timezone_id_arr = array('America/New_York', 'US/Pacific', 'US/Central');
    $res_str = '';
    foreach ($timezone_id_arr as $timezone_id_entry) {
        $res_str .= "\nCreating IntlDateFormatter with timezone_id = {$timezone_id_entry}";
        $fmt = ut_datefmt_create("de-DE", IntlDateFormatter::SHORT, IntlDateFormatter::SHORT, $timezone_id_entry, IntlDateFormatter::GREGORIAN);
        $timezone_id = ut_datefmt_get_timezone_id($fmt);
        $res_str .= "\nAfter call to get_timezone_id :  timezone_id= {$timezone_id}";
        $res_str .= "\n";
    }
    return $res_str;
}
function ut_main()
{
    $timezone_id_arr = array('America/New_York', 'America/Los_Angeles', 'America/Chicago', 'CN');
    $timestamp_entry = 0;
    $res_str = '';
    $fmt = ut_datefmt_create("en_US", IntlDateFormatter::FULL, IntlDateFormatter::FULL, 'America/San_Francisco', IntlDateFormatter::GREGORIAN);
    $timezone_id = ut_datefmt_get_timezone_id($fmt);
    $res_str .= "\nAfter creation of the dateformatter :  timezone_id= {$timezone_id}\n";
    foreach ($timezone_id_arr as $timezone_id_entry) {
        $res_str .= "-----------";
        $res_str .= "\nTrying to set timezone_id= {$timezone_id_entry}";
        ut_datefmt_set_timezone_id($fmt, $timezone_id_entry);
        $timezone_id = ut_datefmt_get_timezone_id($fmt);
        $res_str .= "\nAfter call to set_timezone_id :  timezone_id= {$timezone_id}";
        $formatted = ut_datefmt_format($fmt, 0);
        $res_str .= "\nFormatting timestamp=0 resulted in  {$formatted}";
        $formatted = ut_datefmt_format($fmt, 3600);
        $res_str .= "\nFormatting timestamp=3600 resulted in  {$formatted}";
        $res_str .= "\n";
    }
    return $res_str;
}