Excel cell value update macro

Question

I have a spread sheet for tracking different savings, so column A has a name, B has a currency value. I want to be able to enter a value in column C and have it update the B cell next to it, then return to 0. For example:

B1 = £50.00

I type -£12.00 in C1

B1 = £38.00

C1 = £0.00

I thought there would be a built in function, but I can't find one. I think I will need to write a macro to do this. Can anyone show me how this would be done?

Answer 1

You'll want to add the following code to the sheet your working on. Right Click the sheet name Tab and choose View code and paste this in.

Private Sub Worksheet_Change (ByVal Target as Range)

Dim FirstNum as Currency 'Long is for number currency should help keep format 
Dim SecNum as Currency 

If Target.Column = 3 Then  'Only Runs if Cell being changed is in column C, Might need to be Columns 
    Application.EnableEvents = False ' Stop macro changes calling function repeatedly
    FirstNum = Target.offset(-1,0).Value ' Value in Column B 
    SecNum = Target.Value   ' Value being typed in C  
Target.Offset(-1,0).Value =  FirstNum - SecNum ' Makes Cell B equal to difference of previous value and value typed in C 
     MsgBox("Difference Found") ' Just to display code worked Remove when confirm code works
    Target.Clear ' Clears Value you typed 
    Application.EnableEvents = True ' Re-enable the macro call
End if 

End Sub   

Answer 2

Seems like you are wanting to do something here that is a little different to the way that excel would normally work. Suggest you use more rows then you wouldn't need a macro. eg B1 = $50 C1=-$12 then B2==IF(C1<>"",B1+C1,""). Then you copy cell B1 down to propegate the formulae in cells below. You enter you next value in C2. Does this do what you need?