Question

i want to know the time difference between two countries.
There is ofcourse the static time difference, but during some periods the daylight saving time comes in between.
As far as i know the dst period is also different for some countries, so june 1 the diff between country a and b can be 1 hour, 1 july it can be 2 hours due to DST, and 1 august it can be 1 again etc etc

Is there a framework function for it or do i have to calculate it myself?

Michel

Answer 1

You need to know:

• Both time zones (use TimeZoneInfo from .NET 3.5, bearing in mind that one country can have several time zones)
• An instant in time, e.g. a UTC DateTime or a DateTimeOffset.

At that point it’s relatively easy: convert the UTC instant into the local time in both time zones using TimeZoneInfo.ConvertTime, and subtract one from the other. Alternatively, use TimeZoneInfo.GetUtcOffset for both of them, and subtract one offset from the other.

Here’s an example to find the current difference between London and Mountain View:

using System;

class Test
{
    static void Main()
    {
        var mountainView = TimeZoneInfo.FindSystemTimeZoneById
            ("Pacific Standard Time");
        var london = TimeZoneInfo.FindSystemTimeZoneById
            ("GMT Standard Time");
        DateTimeOffset now = DateTimeOffset.UtcNow;

        TimeSpan mountainViewOffset = mountainView.GetUtcOffset(now);
        TimeSpan londonOffset = london.GetUtcOffset(now);

        Console.WriteLine(londonOffset-mountainViewOffset); // 8 hours
    }
}