如何查找日期和时间夏时制开始

Question

如果我有用户的时区（例如：澳大利亚/悉尼），如何使用PHP查找夏令时在当地时间开始的日期和时间？

Answer 1

我结束了基于t his ticket的一些代码的工作。

$tz = new DateTimeZone('Australia/Sydney'); 
$transitions = $tz->getTransitions(); 
if (is_array($transitions)) { 
    foreach ($transitions AS $k => $t){ 

     // Look for current year 
     if (substr($t['time'],0,4) == date('Y')) { 

      // If isdst is set to 1, that means daylight savings starts on this date 
      if (!empty($t['isdst'])) { 

       $trans = $t; 

      // If isdst is empty, that means daylight savings has already started 
      // so I'll go back to the previous transition 
      } else { 

       $prev_k = $k - 1; 
       $trans = $transitions[$prev_k]; 

      } 

      break; 

     } 
    } 
} 

echo '<pre>'; 
print_r($trans); 
echo '</pre>';