Count Days Between Two Dates (with or without weekends)

Option Explicit
Public Sub Test_CountDays()
'Number of Days between now and 10 days ago, excluding all weekend days
MsgBox CountDays(Now - 10, Now, True)
End Sub
Public Function CountDays( _
          dtFirstDate As Date, _
          dtSecondDate As Date, _
          Optional fNoWeekend As Boolean = True _
          ) As Integer
  
Dim dtFirstDateTemp   As Date   'Hold date to do calculations with
dtFirstDateTemp = dtFirstDate
Dim intWeekendDays   As Integer 'Holds weekend days
If dtFirstDate > dtSecondDate Then
  Exit Function  'Stops you from messing up this calculation, returns "0"
  
Else
  If fNoWeekend = True Then
    Do
      If (Weekday(dtFirstDateTemp) Mod 6 = 1) Then
        intWeekendDays = intWeekendDays + 1
      End If
      
      dtFirstDateTemp = DateAdd("d", 1, dtFirstDateTemp)
      
    Loop Until DateSerial(Year(dtFirstDateTemp), _
          Month(dtFirstDateTemp), _
          Day(dtFirstDateTemp)) _
          = DateSerial(Year(dtSecondDate), _
          Month(dtSecondDate), _
          Day(dtSecondDate))
  
    CountDays = CInt(DateDiff("d", dtFirstDate, dtSecondDate - intWeekendDays))
    
  Else
  
    CountDays = CInt(DateDiff("d", dtFirstDate, dtSecondDate))
    
  End If
  
End If
End Function