Check if Dates Intersect?

Question

I have two Classes which are made up of two DateTime values. A start Date and an End Date.

Basically, I need a way of checking if one of the classes Start Date - End Date range intersects with the other Classes'.

Is there an easy way to do this?

Cheers.

`If a.start < b.end AND a.end > b.start` then A & B intervals intersect — zerkms, Apr 25 '12 at 02:12
@zerkms That won't detect all intersections. If a.start > b.start AND a.start < b.end AND a.end > b.end ... — Nick, Apr 25 '12 at 08:14
@Nick: can you give an example when my condition `a.start < b.end AND a.end > b.start` would fail? — zerkms, Apr 25 '12 at 08:18

David Z. · Accepted Answer · 2012-04-25T02:34:56.110

Here are the possible ways in which the time can overlap (assuming one object starts earlier and one starts later).

time  ----------------------------------------------------------> 

(complete overlap) 
earlier :     start |------------------------------------| end   
later   :          start |--------------------------| end

(partial overlap) 
earlier :       start |--------------------------------| end
later   :           start |--------------------------------| end   

(start date matches)
earlier :       start |----------------------------------| end
later   :       start |----------------------------------| end

(no overlap)
earlier :       start |------------| end
later   :                                start |--------| end

If that's the case, you can do the following to check (though there's

var earlier = obj1.start < obj2.start ? obj1 : obj2;
var later   = obj2.start < obj2.start ? obj1 : obj2;

if (later.start < earlier.end)
{
    Console.WriteLine("Object 1 overlaps with Object 2");
}

Or you can use a single comparison that I proposed in the comments :-) — zerkms, Apr 25 '12 at 06:53

score 2 · Answer 2 · answered Apr 25 '12 at 05:31

You can use the free Time Period Library for .NET:

// ----------------------------------------------------------------------
public void TimeRangeSample()
{
  // --- time range 1 ---
  TimeRange timeRange1 = new TimeRange(
    new DateTime( 2011, 2, 22, 14, 0, 0 ),
    new DateTime( 2011, 2, 22, 18, 0, 0 ) );
  Console.WriteLine( "TimeRange1: " + timeRange1 );
  // > TimeRange1: 22.02.2011 14:00:00 - 18:00:00 | 04:00:00

  // --- time range 2 ---
  TimeRange timeRange2 = new TimeRange(
    new DateTime( 2011, 2, 22, 15, 0, 0 ),
    new TimeSpan( 2, 0, 0 ) );
  Console.WriteLine( "TimeRange2: " + timeRange2 );
  // > TimeRange2: 22.02.2011 15:00:00 - 17:00:00 | 02:00:00

  // --- time range 3 ---
  TimeRange timeRange3 = new TimeRange(
    new DateTime( 2011, 2, 22, 16, 0, 0 ),
    new DateTime( 2011, 2, 22, 21, 0, 0 ) );
  Console.WriteLine( "TimeRange3: " + timeRange3 );
  // > TimeRange3: 22.02.2011 16:00:00 - 21:00:00 | 05:00:00

  // --- relation ---
  Console.WriteLine( "TimeRange1.GetRelation( TimeRange2 ): " +
                     timeRange1.GetRelation( timeRange2 ) );
  // > TimeRange1.GetRelation( TimeRange2 ): Enclosing
  Console.WriteLine( "TimeRange1.GetRelation( TimeRange3 ): " +
                     timeRange1.GetRelation( timeRange3 ) );
  // > TimeRange1.GetRelation( TimeRange3 ): EndInside
  Console.WriteLine( "TimeRange3.GetRelation( TimeRange2 ): " +
                     timeRange3.GetRelation( timeRange2 ) );
  // > TimeRange3.GetRelation( TimeRange2 ): StartInside

  // --- intersection ---
  Console.WriteLine( "TimeRange1.GetIntersection( TimeRange2 ): " +
                     timeRange1.GetIntersection( timeRange2 ) );
  // > TimeRange1.GetIntersection( TimeRange2 ):
  //             22.02.2011 15:00:00 - 17:00:00 | 02:00:00
  Console.WriteLine( "TimeRange1.GetIntersection( TimeRange3 ): " +
                     timeRange1.GetIntersection( timeRange3 ) );
  // > TimeRange1.GetIntersection( TimeRange3 ):
  //             22.02.2011 16:00:00 - 18:00:00 | 02:00:00
  Console.WriteLine( "TimeRange3.GetIntersection( TimeRange2 ): " +
                     timeRange3.GetIntersection( timeRange2 ) );
  // > TimeRange3.GetIntersection( TimeRange2 ):
  //             22.02.2011 16:00:00 - 17:00:00 | 01:00:00
} // TimeRangeSample

Check if Dates Intersect?

2 Answers2