Cell is equal to another cell until you write something in it

[SamT]

Usually means that Application.EnableEvents was not disabled and the _Change event kept calling itself

Yep, Probably what's happening.

Sheet1 code:

Option Explicit

Private Sub Worksheet_Calculate()
'Necessary with Formulas in A1
        CheckB1 
End Sub

Private Sub Worksheet_Change(ByVal Target As Range)
Application.enableEvents = False
        If Not Intersect(Target, Range("A1")) Is Nothing Then CheckB1 'A1 changed
Application.enableEvents = True
End Sub

Private Sub CheckB1()
        If Sheet2.Range("B1") = "" Then Sheet2.Range("B1") = Range("A1")
End Sub

Sheet2 code:

Option Explicit

Private Sub Worksheet_Change(ByVal Target As Range)
Application.enableEvents = False
        If Not Intersect(Target, Range("B1")) Is Nothing Then CheckA1 'B1 changed
Application.enableEvents = True
End Sub

Private Sub CheckA1()
    If Range("B1") = "" Then Range(" B1") = Sheet2.Range("A1")
End Sub

BTW, with With Target.Cells(1, 1), What happens when Range("A1:C1") = Range("A2:C2")

That's why I like If Not Intersect(Target, Range("blah")) Is Nothing

[Paul_Hossler]

Yep, Probably what's happening.

BTW, with With Target.Cells(1, 1), What happens when Range("A1:C1") = Range("A2:C2")

That's why I like If Not Intersect(Target, Range("blah")) Is Nothing

Probably habit

My thinking is that (as you say) multiple cells might be selected, but I wanted to ensure that I'm acting on the one that I think I want to, so I test for the first cell in Target

If Target was A1:C1 (3 cells changed), then Target.Cells(1,1) = A1

If Target was A2:C2 (3 cells changed), then Target.Cells(1,1) = A2 so Exit Sub

If Target was D10:F20 (33 cells changed) AND the desired action was to update (for ex) column G10:G20 with 2 x D1020, I'd use your way

Again, just habit and personal preference.

I'm not worried -- I'm sure someone here will tell me why it's wrong so maybe I'll learn some thing