Conditional Subtraction in VBA - vba

Question

Looking for some assistance programming a report. I'm in the early stages. I've hit a wall when attempting to conditionally subtract using VBA. I would like to Subtract 1 from Column C if Column B is greater than 1. Any assistance would be greatly appreciated. The code I have so far is below
Sub UniqueContactReport()
Columns("Z:AQ").EntireColumn.Delete
Columns("X").EntireColumn.Delete
Columns("V").EntireColumn.Delete
Columns("U").EntireColumn.Delete
Columns("J:S").EntireColumn.Delete
Columns("A:H").EntireColumn.Delete
Dim N As Long, i As Long
N = Cells(Rows.Count, "B").End(xlUp).Row
For i = N To 1 Step -1
If Cells(i, "B") > 1 And Cells(i, "D") = 0 Then
Cells(i, "B").EntireRow.Delete
End If
Next i
End Sub

Answer 1

To succinctly address your question:
Sub ModifyColumnC()
Dim N As Long, i As Long
N = Cells(Rows.Count, "B").End(xlUp).Row ' See comment below
For i = 1 to N 'no need to go backwards because you are not deleting
If Cells(i, "B").Value > 1 Then
Cells(i, "C").Value = Cells(i,"C").Value -1
End If
Next i
End Sub
I have added .Value simply because I try to avoid implicit code. But yes, .Value is the default behaviour. I have left the code that determines the end row because all the following rows are going to be blank (thus <1) and this saves processing time (potentially a lot of it).
An alternative piece of code to do exactly the same thing.
Sub ModifyColumnC()
Dim N As Long, i As Long
N = Cells(Rows.Count, "B").End(xlUp).Row
For i = 1 to N
Cells(i, "C").Value = Cells(i,"C").Value - IIf(Cells(i, "B").Value > 1,1,0)
Next i
End Sub
A nuance is that in the IIf command, all paths are evaluated. But in this case, both the true and false statements are simple constants and unlikely to raise any exceptions.

Answer 2

From your question it seems this is what you want.
Sub UniqueContactReport()
Columns("Z:AQ").EntireColumn.Delete
Columns("X").EntireColumn.Delete
Columns("V").EntireColumn.Delete
Columns("U").EntireColumn.Delete
Columns("J:S").EntireColumn.Delete
Columns("A:H").EntireColumn.Delete
Dim N As Long, i As Long
N = Cells(Rows.Count, "B").End(xlUp).Row
For i = N To 1 Step -1
If Cells(i, "B") > 1 And Cells(i, "D") = 0 Then
debug.print Cells(i, "C").value - 1
End If
Next i
End Sub

Answer 3

you could make no loop and use AutoFilter():
Sub UniqueContactReport()
With Range("B1:B" & Cells(Rows.Count, "B").End(xlUp).Row) 'reference column B cells from row 1 down to last not empty one
.AutoFilter field:=1, Criteria1:=">1" ' filter referenced range on their value being >1
If Application.WorksheetFunction.Subtotal(103, .Cells) > 1 Then ' if any filtered cell other then the header (first one)
With .Offset(1).Resize(.Rows.Count - 1).SpecialCells(xlCellTypeVisible).Offset(, 1) ' reference filtered cells corresponding ones one colum to the right
.Value = .Value - 1 ' lower referenced cell value by one
End With
If .Cells(1, 1).Value > 1 Then .Cells(1, 2) = .cell(1, 2) - 1 ' check if first cell is to be treated, too (first cell of filtered range is assumed as the "header" so doesn't get caught in filter action)
End If
.Parent.AutoFilterMode = False ' remove autofilter
End With
End Sub
BTW you can collapse all those EntireColumn.Delete statements into one:
Range("Z1:AQ1,X1, V1, U1, J:S, A:H").EntireColumn.Delete
but in this case you have to properly adjust the columns reference in the list since columns get deleted in one shot i.e. what-you-list-is-what-gets-deleted while in your previous approach the order of the delete statements affects which original columns gets actually deleted