Updating checkbox value within CheckBox1_Click event runs code twice - excel

Question

I want the checkbox stays the same and generates a message box.
Private Sub CheckBox1_Click()
Dim beast As String
beast = Range("k1").Value
If beast = "No" Then
CheckBox1 = False
MsgBox "You Are Missing Ingredients", vbCritical, "Missing Ingredients"
End If
End Sub

Answer 1

Disable application events. Application events for ActiveX controls are trapped by the code sheet belonging to the worksheet on which the control has been installed. Therefore the code below must be on that code sheet, not a standard code module where it will never run.
Private Sub CheckBox1_Click()
Dim beast As String
With CheckBox1
If .Value = True Then
beast = Range("K1").Value
If beast = "No" Then
MsgBox "You Are Missing Ingredients", vbCritical, "Missing Ingredients"
' prevent the upcoming change from triggering this event
Application.EnableEvents = False
.Value = False
Application.EnableEvents = True
End If
End If
End With
End Sub
Make sure that your check box is an ActiveX control. In fact, once you create such a control it will be listed in the controls drop-down on the top left of the sheet's code module and VBA will create or select the click event procedure for you.
I have tested the above code and it doesn't run more thna once on one click. I have added a check to let it do nothing if the checkmark was removed rather than set.

Answer 2

You can use a static boolean variable to avoid the double execution, like so:
Private Sub CheckBox1_Click()
Static isBusy As Boolean
Dim beast As String
If Not isBusy Then
isBusy = True
beast = Range("k1").Value
If beast = "No" Then
CheckBox1.Value = False
MsgBox "You Are Missing Ingredients", vbCritical, "Missing Ingredients"
End If
isBusy = False
End If
End Sub
Static variables maintain their values across invocations, so if you set it in the first CheckBox1_Click invocation, you can check it in the second one and know a first invocation is ongoing.