How do you recover the number of seconds stored in a DateTime object?

From the Documentation:

Fine. How do I get that value in a Double or whatever.

Var nowDate As DateTime nowDate = DateTime.Now

Can I find out how many seconds there have been since 12:00 AM, January 1, 1970?
i.e. what is the number of seconds that nowDate is storing?

well according to the LangRef

dim seconds as double =nowDate.secondsfrom1970

http://documentation.xojo.com/api/data_types/datetime.html#datetime-secondsFrom1970

Edit: by seconds!

(sorry i ask here)
why it is a double (floating point numbers) and not a long integer???
because milli seconds?

[quote=461515:@Markus Rauch](sorry i ask here)
why it is a double (floating point numbers) and not a long integer???
because milli seconds?[/quote]
They could be used for it. But mainly because Double has a much wider range than Int64: max 1.7 x 10^308.