.NET Date Compare: Count the amount of working days since a date?

Question

What's the easiest way to compute the amount of working days since a date? VB.NET preferred, but C# is okay.

And by "working days", I mean all days excluding Saturday and Sunday. If the algorithm can also take into account a list of specific 'exclusion' dates that shouldn't count as working days, that would be gravy.

Thanks in advance for the contributed genius.

Answer 1

This'll do what you want it to. It should be easy enough to convert to VB.NET, it's been too long for me to be able to do it though.

DateTime start = DateTime.Now;
DateTime end = start.AddDays(9);
IEnumerable<DateTime> holidays = new DateTime[0];

// basic data
int days = (int)(end - start).TotalDays;
int weeks = days / 7;

// check for a weekend in a partial week from start.
if (7- (days % 7) <= (int)start.DayOfWeek)
    days--;
if (7- (days % 7) <= (int)start.DayOfWeek)
    days--;

// lose the weekends
days -= weeks * 2;

foreach (DateTime dt in holidays)
{
    if (dt > start && dt < end)
        days--;
}

Answer 2

The easiest way is probably something like

DateTime start = new DateTime(2008, 10, 3);
DateTime end = new DateTime(2008, 12, 31);
int workingDays = 0;
while( start < end ) {
  if( start.DayOfWeek != DayOfWeek.Saturday
   && start.DayOfWeek != DayOfWeek.Sunday ) {
      workingDays++;
  }
  start = start.AddDays(1);
}

It may not be the most efficient but it does allow for the easy checking of a list of holidays.

Answer 3

Here is a sample of Steve's formula in VB without the holiday subtraction:

Function CalcBusinessDays(ByVal DStart As Date, ByVal DEnd As Date) As Decimal

        Dim Days As Decimal = DateDiff(DateInterval.Day, DStart, DEnd)
        Dim Weeks As Integer = Days / 7
        Dim BusinessDays As Decimal = Days - (Weeks * 2)
        Return BusinessDays
        Days = Nothing
        Weeks = Nothing
        BusinessDays = Nothing

End Function

Answer 4

DateDiff along with a few other Date* functions are unique to VB.NET and often the subject of envy from C# developers. Not sure it'll be very helpful in this case, though.

Answer 5

in general (no code) -

• subtract the dates to get the number of days
• divide by 7 to get the number of weeks
• subtract number of weeks times 2
• count the number of holiday dates that fall with the date range
• subtract that count

fiddle with the start/end dates so that they fall monday to monday, then add back the difference

[apologies for the no-code generalities, it's late]

[c.f. endDate.Subtract(startDate).TotalDays]

Answer 6

Here's a method for SQL Server. There's also a vbscript method on the page. Not exactly what you asked for, I know.

Answer 7

We combined two CodeProject articles to arrive at a complete solution. Our library is not concise enough to post as source code, but I can point you to the two projects we used to achieve what we needed. As always with CodeProject articles, read the comments, there may be important info in them.

Calculating business days:http://www.codeproject.com/KB/cs/busdatescalculation.aspx

An alternative business day calc: http://www.codeproject.com/KB/cs/datetimelib.aspx

Calculating Holidays:http://www.codeproject.com/KB/dotnet/HolidayCalculator.aspx