title: Delphi - equivalent to C# DateTime.IsDaylightSavingTime() method needed
body: <p>I need somehow to determine whether some <code>TDateTime</code> value is within the Daylight Saving Time range for my timezone or not (in C# the same thing does the <code>DateTime.IsDaylightSavingTime()</code> method).</p>
  
  <p>I know in Delphi there's no similar function, because Delphi <code>TDateTime</code> contains no information about timezone, but I suppose there's some way how to do this using Win32 API.</p>
  
  <p>I've looked at Win32 API <code>GetTimeZoneInformation</code> and <code>GetTimeZoneInformationForYear</code> functions, but I don't quite understand how to use them, so I'd like to ask you for help. Thanks in advance for any tips.</p>
  
  <p><strong>Edit:</strong></p>
  
  <p>Example:</p>
  
  <p>In my timezone (Central European) Daylight Saving Time started this year on
  28th March at 2 am and ends on 31st October 2010 at 3 am.</p>
  
  <p>I need a function with header:</p>
  
  <pre><code>function IsDaylightSavingTime(input: TDateTime): boolean;
  </code></pre>
  
  <p>that will return <code>true</code> if the input date is between 28th March 2010 2:00 and 31st October 2010 3:00 and <code>false</code> if not.</p>
  
  <p>(The example is just for year 2010, but I'd need it to work for all years.)</p>
  
  <p>Once again, I know that information saved in TDateTime alone is not enough, but I think that with some Win32 API function I should be able to get e.g. information about current timezone from Windows settings.</p>