Question

I’ve got an asp.net application that must run some code every day at a specific time in the Eastern Time Zone (DST aware). So my first thought is, get the eastern time value and convert it to local server time.

So I need something like this:

var eastern = DateTime.Today.AddHours(17); // run at 5pm eastern
var timeZoneInfo = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
var utc = TimeZoneInfo.ConvertTimeToUtc(eastern, timeZoneInfo);
var local = TimeZoneInfo.ConvertTimeFromUtc(utc, TimeZoneInfo.Local);

But how do I specify that the eastern DateTime object should be in the EST timezone.

Am I approaching this the wrong way?

Answer 1

Seems I was able to answer my own question. Here’s the code I’m using to get a next-run DateTime object.

    private DateTime GetNextRun()
    {

        var today = DateTime.Today;
        var runTime = new DateTime(today.Year, today.Month, today.Day, 17, 0, 0);
        var timeZoneInfo = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
        var offset = timeZoneInfo.GetUtcOffset(runTime);
        var dto = new DateTimeOffset(runTime, offset);

        if (DateTime.Now > dto.LocalDateTime) 
            dto = dto.AddDays(1);

        return dto.LocalDateTime;
    }

Doing all the conversion using DateTimeOffset instead of DateTime proved effective. It even seems to handle Daylight Savings Time correctly.