How can I force user to enter negative number in Excel? - excel

Question

How can I force user to enter negative number in Excel?
Basically column A can only be "W" or "X". Whenever column A has "W", i want column B to reflect a negative number, even if the user has keyed in a positive number.
"W" in column A corresponds to a negative value in column B
"X" in column B corresponds to a positive value in column B.
Thanks for the help!

Answer 1

No VBA needed. Just use data validation with the following formula
=OR(AND(A1="W",B1<0),AND(A1="X",B1>0))
Image 1: Using data validation W in column A only allows negatives in column B, X in column A only allows positives in column B.

Answer 2

Install the code below in the code module of the worksheet on which you want to control the input. It's a module that already exists in your VB Project. Any module you have to create is the wrong one and won't work. Look for a module with a double name like Sheet1 (Sheet1).
Private Sub Worksheet_Change(ByVal Target As Range)
' 058
Dim Rng As Range
Dim Numb As Variant
Dim NewNumb As Double
' ignore changes to more than one cell (such as pasting)
If Target.CountLarge > 1 Then Exit Sub
' this range starts in A2 and covers all used cells in columns A:B
Set Rng = Range(Cells(2, "A"), Cells(Rows.Count, "A").End(xlUp)) _
.Resize(, 2)
' skip if the changed cell is not within the defiend range
If Not Application.Intersect(Target, Rng) Is Nothing Then
' take no action of the value in column A isn't "X" or "W"
With Target
Numb = Cells(.Row, "B").Value
' take no action if the cell in column B has no value
If Numb Then
If Cells(.Row, "A").Value = "W" Then
NewNumb = Abs(Val(Numb)) * -1
ElseIf Cells(.Row, "A").Value = "X" Then
NewNumb = Abs(Val(Numb))
End If
' prevent changes made from calling this procedure
Application.EnableEvents = False
' don't take action if the value in column A
' was neither X nor W
If Numb And (Numb <> NewNumb) Then _
Cells(.Row, "B").Value = NewNumb
Application.EnableEvents = True
End If
End With
End If
End Sub
The code works on columns A and B. To modify these targets isn't difficult. For now, when a cell in either column is changed the procedure may take action. For the rules by which it will not take action please read the comments in the code. When it does take action it will make sure that any entry in column B is negative if the letter in column A is W and positive when it's X, regardless of what sign the user entered.

Answer 3

A little VBA in your worksheet module will take care of that:
Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)
Const SourceColumn As Long = 1
Const TargetColumn As Long = 2
Const NegatorSymbol As String = "W"
Dim SourceRange As Excel.Range
Dim TargetRange As Excel.Range
Dim Sign As Long
Dim TargetValue As Long
If Target.Column = TargetColumn Then
Set SourceRange = Cells(Target.Row, SourceColumn)
If UCase(SourceRange.Value) = NegatorSymbol Then
Sign = -1
Else
Sign = 1
End If
TargetValue = Sign * Abs(Target.Value)
If Target.Value <> TargetValue Then
Target.Value = TargetValue
End If
ElseIf Target.Column = SourceColumn Then
Set TargetRange = Cells(Target.Row, TargetColumn)
If UCase(Target.Value) = NegatorSymbol Then
Sign = -1
Else
Sign = 1
End If
TargetValue = Sign * Abs(TargetRange.Value)
If TargetRange.Value <> TargetValue Then
TargetRange.Value = TargetValue
End If
End If
End Sub

Answer 4

You can set on column B a data validation Custom with this formula:
=OR(AND(A1="W";B1<0);AND(A1<>"W";B1>0))
[EDIT]
I was late to the party...