C# seconds since specific date

Question

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

Answer 1

Goes like this:

  TimeSpan test = DateTime.Now - new DateTime(2010, 01, 01);
  MessageBox.Show(test.TotalSeconds.ToString());

For one liner fun:

 MessageBox.Show((DateTime.Now - new DateTime(2010, 01, 01))
     .TotalSeconds.ToString());

Answer 2

You can substract 2 DateTime instances and get a TimeSpan:

DateTime date = new DateTime(2010,1,1);
TimeSpan diff = DateTime.Now - date;
double seconds = diff.TotalSeconds;

Answer 3

Just to avoid timezone issues

 TimeSpan t = (DateTime.UtcNow - new DateTime(2010, 1, 1));

 int timestamp  = (int) t.TotalSeconds;

 Console.WriteLine (timestamp);

Answer 4

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.

Answer 5

protected void Page_Load(object sender, EventArgs e)
{
    SecondsSinceNow(new DateTime(2010, 1, 1, 0, 0, 0));
}

private double SecondsSinceNow(DateTime compareDate)
{
    System.TimeSpan timeDifference = DateTime.Now.Subtract(compareDate);
    return timeDifference.TotalSeconds;
}

Answer 6

DateTime t1 = DateTime.Now;
DateTime p = new DateTime(2010, 1, 1);

TimeSpan d = t1 - p;

long s = (long)d.TotalSeconds;
MessageBox.Show(s.ToString());