MS-Excel Networkingdays formula subject to workweek - vba

Question

I managed to use the following formula to calculate the net working days between two dates.The problem is i would like to make it possible for the user to enter what days of the week the person works in another cell and automatically update the formula. Just to make it more user friendly, and prevent the user from messing with the formula. Is there anyway to enter the string(12345) in another cell and have the formula update automatically?
Thanks in advance
Option Explicit
'
' This function tells you how many working days are there between 2 given dates.
' You can use this to calculate working days in countries where saturday and sunday are
' not usually holidays.
'
Function NetWorkingDays(sDateRng As Range, eDateRng As Range, workingDays As String, _
Optional HolidayRng As Range) As Long
'
' e.g. use: =NetWorkingDays($A$1,$A$2,"12356")
' will tell you the count of mondays, tuesdays, wednesdays, fridays and saturdays
' between the dates in $A$1 and $A$2
'
' e.g. use: =NetWorkingDays($A$1,$A$2,"12356",$H$2:$H$50)
' will tell you the count of mondays, tuesdays, wednesdays, fridays and saturdays
' between the dates in $A$1 and $A$2, excluding any holidays (listed as dates) in
' the range $H$2:$H$50
'
' You can also count the number of individual days between dates:
' =NetWorkingDays($A$1,$A$2,"2")
' will tell you the number of tuesdays between those two dates
'
Dim sDate As Date, eDate As Date, Holidays() As Variant
Dim nHolidays As Long
Dim totalDays, startDay As Long, endDay As Long
Dim totWeeks As Long, extraDays As Long
Dim curWeekday As Long
Dim i, retVal As Long
'
If (Not IsDate(sDateRng.Value)) Then
sDate = 0#
Else
sDate = sDateRng.Value
End If
'
If (Not IsDate(eDateRng.Value)) Then
eDate = 0#
Else
eDate = eDateRng.Value
End If
'
If (Not HolidayRng Is Nothing) Then
nHolidays = HolidayRng.Cells.Count
ReDim Holidays(0 To nHolidays - 1)
Holidays = HolidayRng.Value2 ' CAREFUL - this automatically assumes dates in the range!
Else
nHolidays = 0
End If
'
totalDays = eDate - sDate + 1
startDay = Weekday(sDate, vbMonday)
endDay = Weekday(eDate, vbMonday)
'
' First calculate the number of whole weeks in the date span.
' Whole weeks are defined as all weeks that start on Monday and
' end on Sunday.
'
If (startDay = 1) Then
If (endDay = 7) Then
extraDays = 0
Else
extraDays = 7 - endDay
End If
Else
If (endDay = 7) Then
extraDays = 7 - startDay + 1
Else
extraDays = 7 - startDay + 1 + endDay
End If
End If
totWeeks = (totalDays - extraDays) / 7
'
' Now determine how many "extra" days are on either side of
' the whole weeks. Include only those "extra" days that are
' a part of the "workingDays" string.
'
extraDays = 0
If (startDay <> 1) Then
For i = startDay To 7
If (InStr(workingDays, CStr(i)) > 0) Then
extraDays = extraDays + 1
End If
Next i
End If
If (endDay <> 7) Then
For i = 1 To endDay
If (InStr(workingDays, CStr(i)) > 0) Then
extraDays = extraDays + 1
End If
Next i
End If
'
retVal = totWeeks * Len(workingDays) + extraDays
'
' Now subtract out the holidays if applicable to the period in question
'
If (nHolidays > 0) Then
For i = LBound(Holidays) To UBound(Holidays)
If (InStr(workingDays, Weekday(Holidays(i, 1), vbMonday)) > 0 And _
Holidays(i, 1) >= sDate And Holidays(i, 1) <= eDate) Then
retVal = retVal - 1
'Debug.Print Format(Holidays(i, 1), "dd mmm, yyyy") & " was removed: it is a " & Format(Holidays(i, 1), "dddd")
Else
'Debug.Print Format(Holidays(i, 1), "dd mmm, yyyy") & " was not removed: it is a " & Format(Holidays(i, 1), "dddd")
End If
Next i
End If
'
NetWorkingDays = retVal
End Function