更改时区之间的日期和时间

Question

我一直在尝试在给定日期和时间之间的时区之间进行转换。
代码比语言更多，所以这里是：

/** 
* Returns the date and time in the new timezone. 
* 
* @param string $datetime: 
*   the date and time to change between timezones 
* @param string $input_tz: 
*   the input timezone 
* @param string $output_tz: 
*   the output timezone 
* @return string The new date and time 
*/ 
public function changeDateTime($datetime, $input_tz, $output_tz) { 
    if($input_tz == $output_tz) return $datetime; 
    /* 
    * We calculate the hour and minute offset from GMT 
    */ 
    date_default_timezone_set($output_tz); 
    $out_dst = date('I', $datetime) ? 1 : 0; 
    $out_hour_offset = intval(substr(date('O', $datetime), 1, 3)) + $out_dst; 
    $out_minute_offset = intval(substr(date('O', $datetime)), - 2); 

    date_default_timezone_set($input_tz); 
    $in_dst = date('I', $datetime) ? 1 : 0; 
    $in_hour_offset = intval(substr(date('O', $datetime), 1, 3)) + $in_dst; 
    $in_minute_offset = intval(substr(date('O', $datetime)), - 2); 

    /* 
    * We subtract hour and minute offsets to come up with total difference 
    */ 
    $hour_offset = $out_hour_offset - $in_hour_offset; 
    $minute_offset = $out_minute_offset - $in_minute_offset; 

    /* 
    * Now we must take care of changing the day/month/year if necessary, as 
    * well as the hour/minute for $datetime, and return that value. 
    */ 
    $date = new DateTime($datetime); 
    if($hour_offset > 0) { 
     $date->add(date_interval_create_from_date_string($hour_offset . ' hours')); 
     if($minute_offset > 0) $date->add(date_interval_create_from_date_string($minute_offset . ' minutes')); 
    } else if($hour_offset < 0) { 
     $date->sub(date_interval_create_from_date_string($hour_offset . ' hours')); 
     if($minute_offset > 0) $date->sub(date_interval_create_from_date_string($minute_offset . ' minutes')); 
    } 
    return $date->format('Y-m-d H:i:s'); 
} 

但是，它似乎并没有很好地工作。这是我正在测试它是否工作或不代码：

$newdatetime = $gato->changeDateTime("2012-08-10 11:33:33", 'Europe/London', 'Europe/Madrid'); 
echo $newdatetime; 

这是我期望的输出：2012-08-10 12点33分三十三秒
但是，这是我的实际输出：2012- 08-10 11:33:33，这意味着没有时间变化。

Answer 1

OK，试试这个来代替：

function changeDateTime($datetime, $input_tz, $output_tz) { 

    // Return original string if in and out are the same 
    if($input_tz == $output_tz) { 
     return $datetime; 
    } 

    // Save current timezone setting and set to input timezone 
    $original_tz = date_default_timezone_get(); 
    date_default_timezone_set($input_tz); 

    // Get Unix timestamp based on input time zone 
    $time = strtotime($datetime); 

    // Start working in output timezone 
    date_default_timezone_set($output_tz); 

    // Calculate result 
    $result = date('Y-m-d H:i:s', $time); 

    // Set timezone correct again 
    date_default_timezone_set($original_tz); 

    // Return result 
    return $result; 

} 

$out = changeDateTime("2012-08-10 11:33:33", 'Europe/London', 'Europe/Madrid'); 
var_dump($out); 

而不是搞乱尽一切复杂的数学，只让PHP做所有的辛勤工作为你;-)

See it working