Question

I get date data from a user. That data is a date (e.g. 4/23/2011) and an hour (0 – 23), representing the time. This date/time that the user selects is a local time.

I need to convert this to a UTC DateTime. I have their GMTOffset for their location. How can I do this?

Answer 1

var utcDateTime = 
     new DateTimeOffset(userDateTime, TimeSpan.FromHours(userUtcOffset)).UtcDateTime;

Of course you can use TimeSpan differently if the GMT offset has minutes / fractions of an hour.