Excel VBA - Run a macro when a cell is changed - vba

Question

I am trying to write a macro that runs automatically any time a sheet is edited. Column H has the heading "Updated on" and the macro should put today's date in cell H# where # is the row of the cell that was changed. Here's the code I used:
Private Sub Worksheet_Change(ByVal Target As Range)
Target.Select
Range("H" & ActiveCell.Row).Select
ActiveCell.Value = Date
End Sub
After saving the workbook and changing the value of cell A2, the code put today's date into H2 as I expected, but then gave me an error. I clicked debug, and the Target.Select line was highlighted. I assumed that looping was the problem, so I updated the code:
Private Sub Worksheet_Change(ByVal Target As Range)
Application.EnableEvents = False
Target.Select
Range("H" & ActiveCell.Row).Select
ActiveCell.Value = Date
Application.EnableEvents = True
End Sub
This time, I changed the value of cell B3, and it put today's date into B4. Then Excel partially froze: I could still edit that workbook, but I couldn't open or view any other workbook. I closed all the workbooks, but then Excel itself would not close and I had to use the Task Manager to end it.

Answer 1

Using
Private Sub Worksheet_Change(ByVal Target As Range)
Range("H" & Target.Row).Value = Date
End Sub
will give you better stability. Target is the range that's changed.
It's just possible (I'm at home so can't check) that changing the value re-fires the Worksheet_Change event. If so, then block the recursion with
Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Address <> Range("H" & Target.Row).Address Then
Range("H" & Target.Row).Value = Date
End If
End Sub

Answer 2

Private Sub Worksheet_Change(ByVal Target As Range)
const DATE_COL as long = 8
Dim c as range
Set c = Target.Cells(1)
If c.Column = DATE_COL Then Exit Sub
On Error Goto haveError
Application.EnableEvents=False
Me.Cells(c.Row, DATE_COL).Value = Date
haveError:
Application.EnableEvents=True
End Sub