Passing a string variable to another procedure to assign a value to it in a loop

Question

I want to pass aa string variable "Sheets(2).Cells(i, 41).Value" to the procedure Sub prcdTariff_calc that will assign in a loop a value to that variable in order to pass it on to another function, Function Tariff_calc . The problem is with Sub prcdSum_year_IR() . I tried already to play around with the datatypes (String / Double) in the procedures and also CDbl(quality) etc... Is there a way to pass on the variable quality into the loop in Sub prcdTariff_calc ? Thanks for advice.

  Option Explicit
    Dim  price As String
    Dim i As Byte
    Public  sum_tariff As Double
    Dim tariff As Double, period As Double, quality As Double


    Function Tariff_calc(a As Double, Optional b As Double = 1, Optional c As Double = 1) As Double
    Tariff_calc = a * b * c
    Debug.Print b
    End Function

    Function Price_calc(a As Double, Optional b As String = 1, Optional c As Double = 1) As String
    Price_calc = Format(a * b * c, "0.00   €/MWh")
    End Function

    Sub prcdTariff_calc(Optional a As Double = 1, Optional b As Double = 1, Optional c As Double = 1)
    For i = 2 To 43
        If ThisWorkbook.Sheets(2).Cells(i, 1).Value = 1 Then
            a = Sheets(2).Cells(i, 19).Value
            'I also tried b = val(quality) here
'I experimented here by referring to newly created procedure Sub [prcdquality() quality = Sheets(2).Cells(i, 41) End Sub] and back here then b=quality; and it worked         
            sum_tariff = sum_tariff + Tariff_calc(a, Val(b), c) 'I tried val(b), but it still shows 0 in Debug.Print b above.

            price = Price_calc(a, CStr(b), c)
            lblPrice.Caption = lblPrice.Caption & price & vbCrLf
        End If
    Next i
    End Sub

    Sub prcdSum_year_Firm()'works fine
    prcdTariff_calc
    lblUnitCost.Caption = Format(sum_tariff, "0.00    €/MWh")
    End Sub

    Sub prcdSum_year_IR()
    quality = Sheets(2).Cells(i, 41)
    prcdTariff_calc b:=quality
    lblUnitCost.Caption = Format(sum_tariff, "0.00    €/MWh")
    End Sub

Answer 1

I resolved my problem by modifying the code by declaring the variables a,b,c inside the loop of procedure. It works fine now.

Function Tariff_calc(a As Double, Optional b As Double = 1, Optional c As Double = 1) As Double
Tariff_calc = a * b * c
End Function

Function Price_calc(a As Double, Optional b As String = 1, Optional c As Double = 1) As String
Price_calc = Format(a * b * c, "0.00   €/MWh")
End Function

Sub prcdTariff_calc(Optional a As Double = 1, Optional b As Double = 1, Optional c As Double = 1)
For i = 2 To 43
    If ThisWorkbook.Sheets(2).Cells(i, 1).Value = 1 Then
        a = Sheets(2).Cells(i, 19).Value 'annual tariff
        If optIR.Value Then
           b = Sheets(2).Cells(i, 41) 'quality factor
        End If
        If optQuarter.Value Then
            c = Sheets(2).Cells(i, 21 + q) 'period factor Quarter
        ElseIf optMonth.Value Then
            c = Sheets(2).Cells(i, 28 + m) 'period factor Month
        ElseIf optDay.Value Then
            c = Sheets(2).Cells(i, 27)
        End If

        sum_tariff = sum_tariff + Tariff_calc(a, b, c)

        price = Price_calc(a, CStr(b), c)
        lblPrice.Caption = lblPrice.Caption & price & vbCrLf
    End If
Next i
lblUnitCost.Caption = Format(sum_tariff, "0.00    €/MWh")
End Sub