How to get the number of overlapping days between two ranges?

Question

Let me explain the situation first - let's say I have 4 dates: BS, BE, PS, PE (S for the beginning, E for the end). I need to know how many days are over when these dates are given. for example: BE-05.01, BS-10.01, PS-03.01, PE-07.01 result: 3 (05.01, 06.01 and 07.01 overlap)

I wrote the following code, but it seems to be messy, and I want to check, maybe there is an easier way to do this:

private static double GetNumOfOverLappingDays(DateTime BS, DateTime BE, DateTime PS, DateTime PE)
    {
        //case 1:
        //                  |--- B ---|
        //                  |----P ---|

        //case 2:
        //                  |--- B ---|
        //                          | --- P --- |

        //case 3:
        //                  |--- B ---|
        //          | --- P ---- |

        //case 4:
        //                  |--- B ---|
        //                     | - P - |

        //case 5:
        //                  |--- B ---|
        //              | -------- P -------- |

        double days = -1;
        bool isNotOverLap = (BS > PE) || (PS > BE);

        if (isNotOverLap == false)
        {
            //case 1
            if (BS == PS && BS == PE)
            {
                days = (PE - PS).TotalDays;
            }
            //case 2
            else if (BE > PS && BE < PE)
            {
                days = (BE - PS).TotalDays;
            }
            //case 3
            else if (BS > PS && BS < PE)
            {
                days = (PE - BS).TotalDays;
            }
            //case 4
            else if (BS < PS && BE > PE)
            {
                days = (PE - PS).TotalDays;
            }
            //case 5
            else if (BS > PS && BE < PE)
            {
                days = (BE - PS).TotalDays;
            }
        }
        return days+1;
    }

in advance for any help,

Amit

Answer 1

Try the following:

    private static double GetOverlappingDays(DateTime firstStart, DateTime firstEnd, DateTime secondStart, DateTime secondEnd)
    {
        DateTime maxStart = firstStart > secondStart ? firstStart : secondStart;
        DateTime minEnd = firstEnd < secondEnd ? firstEnd : secondEnd;
        TimeSpan interval = minEnd - maxStart;
        double returnValue = interval > TimeSpan.FromSeconds(0) ? interval.TotalDays : 0;
        return returnValue;
    }

Answer 2

Try using for loop:

DateTime d1 = new DateTime(2013,12,1),
            d2 = new DateTime(2013,12,14),
            d3 = new DateTime(2013,12,10),
            d4 = new DateTime(2013,12,20);
int count = 0;

for (var d = d1.Date; d <= d2.Date; d = d.AddDays(1))
{
      if (d >= d3.Date && d <= d4.Date)
           count++;
}

Console.WriteLine(count);

, . , . , .

Answer 3

, , . DateRange:

public class DateRange
{
    public DateRange(DateTime start, DateTime end)
    {
        if (start > end) throw new ArgumentException();

        Start = start;
        End = end;
    }

    public DateTime Start { get; private set; }
    public DateTime End { get; private set; }
    public double TotalDays { get { return (End - Start).TotalDays; } }

    public bool Includes(DateTime value)
    {
        return (Start <= value) && (value <= End);
    }

    public DateRange Intersect(DateRange range)
    {
        if (range.Includes(Start))
            return new DateRange(Start, (End < range.End) ? End : range.End);

        if (range.Includes(End))
            return new DateRange(range.Start, End);

        if (Start < range.Start && range.End < End)
            return range;

        return null;
    }
}

:

public static double GetNumOfOverLappingDays(DateRange b, DateRange p)
{
   DateRange overlap = b.Intersect(p);
   if (overlap == null)
       return 0;

   return overlap.TotalDays;
}

:

var b = new DateRange(new DateTime(2013, 12, 20), new DateTime(2013, 12, 25));
var p = new DateRange(new DateTime(2013, 12, 22), new DateTime(2013, 12, 26)); 
double totalDays = GetNumOfOverLappingDays(b, p);

Answer 4

, . , , , 5 , .

    static void Main(string[] args)
    {
        DateTime start1 = new DateTime(2013,1,2);
        DateTime end1 = new DateTime(2013,1,14);

        DateTime start2 = new DateTime(2013,1,1);
        DateTime end2 = new DateTime(2013,1,12);

        DateTime lateStart = GetLatest(start1, start2);
        DateTime earlyEnd = GetEarliest(end1, end2);

        Console.WriteLine((earlyEnd-lateStart).TotalDays + 1);
        Console.ReadLine();
    }

    private static DateTime GetEarliest(DateTime start1, DateTime start2)
    {
        return start1 < start2 ? start1 : start2;
    }

    private static DateTime GetLatest(DateTime start1, DateTime start2)
    {
        return start1 > start2 ? start1 : start2;
    }