control arrays problem

[haris-raheem]

hello
i am having a problem with control arrays
i am dynamically loading and unloading the controls
but an error occurs when a element which is unloaded is refenced
i want to apply a condition to know that wether a element at this
index exists or not.
can any one help me.

[sunnyl]

Can you try and just catch the element does not exist error instead?

'assumes a Label1 with Index set to 0
Private Sub Form_Load()
    Load Label1(1)
    Load Label1(2)
    
    Unload Label1(1)
    
    On Error Resume Next
    MsgBox Label1(1).Caption
    
    If Err.Number = 340 Then
        MsgBox "element does not exist"
    End If
End Sub

[chrisjk]

Perhaps you should have a public variable that keeps track of the largest possible element. You can incremenet/decrement at will.

[haris-raheem]

the place where i am using this control array is critical and cannot rely on these errorr detection codes so i want to know that when a control is unloaded then whats is the thing that resides at that index please send an immediate answer

[beachbum]

hi
i am sure u could find a way to put error detection in any sub that accesses a nonexistent control but if u dont want to go that way u could use a piggy back variable that records the status of each control eg

Private Sub Command1_Click(index As Integer)
    Dim IExist() As Boolean
    
    ReDim IExist(4)
    For x = 1 To 4
        Load Command1(x) 'Create at runtime
        IExist(x) = True 'record as existing
    Next
    
    Unload Command1(2) 'unload 2
    IExist(2) = False 'Set corresponding var to false
    
    For x = 1 To 4
        If IExist(x) Then Debug.Print x
    Next
End Sub

[Tygur]

Here is a function I just made real quick. It should be what you're looking for. Give it the control array and the index value you want to check for. It returns true if the control is there and false if it's not:

Private Function IsLoaded(CtrlArray, Index As Long) As Boolean
Dim tVar
On Local Error GoTo GotErr
tVar = CtrlArray(Index).Tag
IsLoaded = True
Exit Function
GotErr:
IsLoaded = False
End Function
 
'Usage
If IsLoaded(Command1, 1) Then
    MsgBox Command1(1).Caption
End If