C# seconds since specific date

Question

In C# 3.0, how do I get the seconds since 1/1/2010?

Answer 1

It's really a matter of whose 2010-Jan-01 you're using and whether or not you wish to account for daylight savings.

//I'm currently in Central Daylight Time (Houston, Texas)
DateTime jan1 = new DateTime(2010, 1, 1);

//days since Jan1 + time since midnight
TimeSpan differenceWithDaylightSavings = DateTime.Now - jan1;

//one hour less than above (we "skipped" those 60 minutes about a month ago)
TimeSpan differenceWithoutDaylightSavings = (DateTime.UtcNow - jan1.ToUniversalTime());

//difference for those using UTC and 2010-Jan-01 12:00:00 AM UTC as their starting point
//   (today it's 5 hours longer than differenceWithDaylightSavings)
TimeSpan utcDifference = (DateTime.UtcNow - new DateTime(2010, 1, 1));

Difference with Daylight Savings:     105.15:44:09.7003571
Difference without Daylight Savings:  105.14:44:09.7003571
UTC Difference:                       105.20:44:09.7003571

To get the seconds, use the TotalSeconds property off the TimeSpan object.