DateTime Comparison Precision

Question

I\'m doing DateTime comparison but I don\'t want to do comparison at second, millisecond and ticks level. What\'s the most elegant way?

If I simply compare the DateT

Answer 1

Very simple solution from my own code:

TimeSpan timeDifference = presentLastSavedDate.Subtract(previousLastSavedDate);
if (timeDifference.Seconds > 0)
{
    return Content(HttpStatusCode.Conflict, ALREADY_CHANGED_MSG);
}

Answer 2

Using a TimeSpan you get all the granularity you want :

DateTime dt1, dt2;
double d = (dt2 - dt1).TotalDays;
double h = (dt2 - dt1).TotalHours;
double m = (dt2 - dt1).TotalMinutes;
double s = (dt2 - dt1).TotalSeconds;
double ms = (dt2 - dt1).TotalMilliseconds;
double ticks = (dt2 - dt1).Ticks;

Answer 3

I've written this to help myself:

    internal class ImpreciseCompareDate : IComparer<DateTime>
{
    private readonly double _Tolerance;

    public ImpreciseCompareDate(double MillisecondsTolerance)
    {
        _Tolerance = MillisecondsTolerance;
    }

    public int Compare(DateTime x, DateTime y)
    {
        return Math.Abs((x - y).TotalMilliseconds) < _Tolerance ? 0 : x.CompareTo(y);
    }
}

Tolerance can be set to (10d/3d) to account for SQL servers 1/300th of a ms. If tolerance is exceeded, delegate to default comparer.

Answer 4

How about this ComparerClass?

public class DateTimeComparer : Comparer<DateTime>
{
    private string _Format;

    public DateTimeComparer(string format)
    {
        _Format = format;
    }

    public override int Compare(DateTime x, DateTime y)
    {
        if(x.ToString(_Format) == y.ToString(_Format))
            return 0;

        return x.CompareTo(y);
    }
}

This can be used by

List.Sort(new DateTimeComparer("hh:mm"));

Answer 5

What about using a timespan.

if (Math.Truncate((A - B).TotalMinutes) == 0)
{
    //There is less than one minute between them
}

Probably not the most elegant way, but it allows for cases which are one second apart and yet have different days/hours/minutes parts such as going over midnight.

Edit: it occured to me that the truncate is unecessary...

if (Math.Abs((A - B).TotalMinutes) < 1)
{
    //There is less than one minute between them
}

Personally I think this is more elegant...

Answer 6

One approach could be to create two new DateTimes from your values you want to compare, but ignore anything from the seconds on down and then compare those:

DateTime compare1 = new DateTime(year1, month1, day1, hour1, minute1, 0);
DateTime compare2 = new DateTime(year2, month2, day2, hour2, minute2, 0);

int result = DateTime.Compare(compare1, compare2);

I'd be the first to admit it's not elegant, but it solves the problem.