Pls help me understand dynamic array

[dave8]

I have a listbox on a form set as MultiSelect and I want to put the rows that were selected in an array. Consider this code:

Dim chkBoxArr() as long
Dim icount, j as integer

For j = 1 To Userform1.Listbox1.ListCount - 1
     If UserForm1.ListBox1.Selected(j) Then
        chkBoxArr(icount) = j
        icount = icount + 1
     End If
  Next j
 
 ReDim Preserve chkBoxArr(j)
 
 For icount = LBound(chkBoxArr) To UBound(chkBoxArr)
    If chkBoxArr(icount) <> 0 Then
      MsgBox chkBoxArr(icount)
  Next icount

I want to put the row number of the check box selected from the listbox into an array. For example, if I select row 2 from the listbox, the number 2 gets put into the array cell; if row 10 gets selected, then the number 10 gets put into the array cell. I can select multiple rows from the listbox and have these row numbers in the array (2, 10, 15, 19, etc). I created a dynamic array because the listbox items can be over several hundred and I only want to display the row numbers in the array.

The problem is that I can't display the array elements. Are these values getting into the array or are they being overwritten?

 

[shg]

Try this:

Sub x()
    Dim aiSel()     As Long
    Dim iSel        As Long
    Dim iList       As Long
 
    With UserForm1.ListBox1
        ReDim aiSel(1 To .ListCount)
 
        For iList = 0 To .ListCount - 1
            If .Selected(iList) Then
                iSel = iSel + 1
                aiSel(iSel) = iList
            End If
        Next iList
 
        ReDim Preserve aiSel(1 To iSel)
 
        For iSel = 1 To iSel
            MsgBox aiSel(iSel)
        Next iSel
    End With
End Sub

 

[dave8]

.

 

[dave8]

Thank you. But, I don't understand why have to ReDim at the beginning? I haven't put anything in it yet?

 

[Norie]

It doesn't matter that you've put nothing in it.

In fact unless you redim it at the start you wouldn't be able to put anything in it.

 

[shg]

Until the array is dimensioned, there is no storage allocated, no there's no place to store anything.

 

[mikerickson]

Dim rowsMatch as Variant
Dim i as Long

rowsMatch = vbNullString

With ListBox1
    For i = 0 to .ListCount - 1
        if .Selected(i) then rowsMatch = "," & i
    Next i
End With

rowsMatch = Split(Mid(rowsMatch,2), ",")

For i = 0 to UBound(rowsMatch)
    MsgBox rowsMatch(i)
Next i

 

[dave8]

Now I understand. Thank you.

 

[dave8]

SHG, you helped me with an array routine and now I want to experiment with some changes. I want to be able to pass the array to a procedure and read from it. I tried it but I just get the first element in the array. How do I pass the array (in the calling procedure) and read all the elements in the called procedure.