I want to change a positive value cell input in a range to a negative value by reference to a criteria in another cell range. So for instance cell range A1:A10 contains either a value of "B" or "S". Cell range B1:B10 is where the numeric values are entered. These values when entered are either made positive or negative values depending on the data already entered in corresponding cells A1:A10. So entering any value whether positive or negative in say B1 as either 1234 or -1234 where A1 has a value "B" will result in B1 displaying -1234. Conversely where any value whether positive or negative is input in Cells B1:B10 and the value of the corresponding row in column A is "S" the value in column B will always be positive irrespective of whether the original input was negative or positive.
If there is no value in a particular cell in the range A1:A10 corresponding to the same row in column B then a message should be displayed to the user saying "Please enter a value in the corresponding row in column A.
I am a complete novice to VBA coding and so far looking at other posts have cobbled together following code, but I do not know how to complete it to work successfully.
Any help would be very much appreciated.
Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)
Dim A1 As Range
Set A1 = Range("A1:A10")
Dim A2 As Range
Set A2 = Range("B1:B10")
If Intersect(Target, A2) Is Nothing Then Exit Sub
If IsText(Target, A1) Then
If A1 = "S" Then
Application.EnableEvents = False
B1 = -B1
Application.EnableEvents = True
End If
End Sub