Hi Kevin, Thank you for the kind insight. But, what my problem really is, is how to extract the timezone setting from the user's local machine and translate it in human language. I believe that the MS TimeZoneInfo class can be the answer to that but I have been breaking my neck over trying to translate the VB example they provide, into Pascal code.
Emmanuel --- In delphi-en@yahoogroups.com, "jumpsfromplanes" <kgmcco...@...> wrote: > > A Delphi TDateTime variable is actually a double precision number, with the > whole number part representing the elapsed days since (I think) 31 December > 1899, and the fractional part representing the time. The time is a fraction > expressed as N/24 where N is in hours. > > Example: > > If the time is 23:30, then N=23.5; > > 23.5/24.0 = 0.9791666666666667 > > So 1.9791666666666667 = 23:30:00 on 1 Jan 1900. > > So if you want to subtract 8 hours, you actually have to subtract "eight > twentyfourths" or > > UTC := PacificTime - (8.0 / 24.0); > > Subtracting 8 from Pacific time would result in the same time, but 8 *days* > before! > > You can use the SysUtils.EncodeTime function to do the fractions for you. In > the context of UTC conversion, it might be easier to do the fractions > yourself, since you usually don't need minutes, and certainly don't need > seconds and milliseconds. > > Doing it yourself also allows you to use positive and negative hour offsets. > EncodeTime only works on positive hour/min/sec/msec values. > > Positive and negative offsets are used in time conversion. > > HTH, > > Kevin G. McCoy > > --- In delphi-en@yahoogroups.com, "Glenn B. Lawler" <gblawler@> wrote: > > > > Emmanuel, > > > > > Does anyone know of a free component that converts the local time to UTC > > and back to another time zone local time? > > > > I am not sure what your application is for these converted times, or what > > time structure you are using. If you are talking about TDateTime, changing > > from one timezone to another is simply a matter of subtracting your UTC > > offset. For example, US Pacific time is -8, so you subtract -8 from the > > current time to calculate UTC time. If it is 1 AM minus -8 is 9 AM. To > > convert from UTC time to another local time, just add the offset. Since > > TDateTime is a numeric (double) type, you can just calculate the number. > > > > If you are talking about file times, there are Windows API calls available. > > GetFileTime returns the CreationTime, LastAccessTime, and LastWriteTime for > > an open file handle. These times are UTC times, if the file system is NTFS. > > FileTimeToLocalFileTime converts a UTC file time to the local time of the > > machine. > > > > If you tell me more about what you are trying to do with these times, I can > > tell you specifically how I would handle the situation. > > > > Glenn Lawler > > www.incodesystems.com > > >
