A better way to construct a datetime with higher precision than milliseconds

Question

I have just gone through an unexpectedly convoluted process to define datetimes.

The underlying data has a better precision than milliseconds.

I ended up constructing an intermediate datetime to the nearest second, reading it's value in ticks (10 000 to the millisecond), adjusting the ticks then creating the datetime that I actually wanted.

I expected constructors that took seconds as doubles and that takes a string date/time format specifier. Neither seems to exist.

Anybody got a good alternate approach?

Answer 1

There is no direct way to instantiate a DateTime based on fractions of a second. The closest you can get, as you have discovered, is using ticks. A function like this should at least save you from having to create multiple DateTimes in every case.

public DateTime DateTimeFromFractionalSeconds(int year, int month, int day, int hour, int minute, double seconds)
{
    return new DateTime(year, month, day, hour, minute).AddTicks((long)(seconds * 1000000000));
}

You're right that the designers could have included such a constructor. However, the DateTime class is not based around seconds any more than it's around minutes. I realize that you want fractional seconds, but can you truly make the case that fractional seconds would be more legitimate than fractional minutes? Or hours? The DateTime class is based around ticks. That is the smallest indivisible unit of measure that it deals with, which is why the most granular constructor is represented in ticks.

Answer 2

If you want to use this date time to time how long it takes to run your code, you'd be much better off using the Stopwatch stopwatch class. It uses a high precision timer that isn't available to the DateTime object. If you aren't timing how long something takes between 2 points, and just want the current time, to something more precise than milliseconds, I think that you are going a bit overboard, and may not need all that precision, or that you the extra precision is meaningless.