UBound Array Definition - vba

Question

Having trouble understanding how to use UBound.
If I have a dynamic column A where the rows count is constantly changing, but I want to grab the upper bound to define in a for loop - how would I go about doing so? I keep getting a runtime error with the below method.
arr = Worksheets("Sheet1").Range("A1").CurrentRegion.Value
For i = 1 to UBound(arr, 1)
etc.
Next i

Answer 1

When setting an array equal to a range value, it automatically sets it as a two dimensional array, even if the range is only one column. Look at the example below:
Private Sub workingWithArrayBounds()
Dim Arr As Variant
Dim RowIndex As Long
Dim ColumnIndex As Long
Arr = Worksheets("Sheet1").Range("A1").CurrentRegion.Value
'VBA FUNCTION FOR CHECKING IF SOMETHING IS AN ARRAY
If IsArray(Arr) Then
'FIRST LOOP GOES THROUGH THE ROWS
For RowIndex = LBound(Arr, 1) To UBound(Arr, 1)
'THE SECOND LOOP GOES THROUGH THE COLUMNS
For ColumnIndex = LBound(Arr, 2) To UBound(Arr, 2)
'NOW YOU HAVE ACCESS TO EACH ELEMENT USING THE ROWINDEX AND THE COLUMN INDEX
Debug.Print Arr(RowIndex, ColumnIndex)
Next
Next
End If
End Sub
If there is only one column of data, the bounds would look something like (1 to x, 1 to 1). So you would need to pass in the second bounds to it. To be safe, it is always recommended to use both the LBound and UBound when looping through arrays as these can vary from array to array.
Another thing to check is if the array is actually allocated. In the scenario of setting an array equal to the value of a range, you can first check if there are values actually in your range to retrieve.
An alternative is to use a function to check and see if array is empty or not. Cpearson has a good function for that as well as many other helpful functions # http://www.cpearson.com/excel/vbaarrays.htm
Public Function IsArrayEmpty(Arr As Variant) As Boolean
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' IsArrayEmpty
' This function tests whether the array is empty (unallocated). Returns TRUE or FALSE.
'
' The VBA IsArray function indicates whether a variable is an array, but it does not
' distinguish between allocated and unallocated arrays. It will return TRUE for both
' allocated and unallocated arrays. This function tests whether the array has actually
' been allocated.
'
' This function is really the reverse of IsArrayAllocated.
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Dim LB As Long
Dim UB As Long
Err.Clear
On Error Resume Next
If IsArray(Arr) = False Then
' we weren't passed an array, return True
IsArrayEmpty = True
End If
' Attempt to get the UBound of the array. If the array is
' unallocated, an error will occur.
UB = UBound(Arr, 1)
If (Err.Number <> 0) Then
IsArrayEmpty = True
Else
''''''''''''''''''''''''''''''''''''''''''
' On rare occassion, under circumstances I
' cannot reliably replictate, Err.Number
' will be 0 for an unallocated, empty array.
' On these occassions, LBound is 0 and
' UBoung is -1.
' To accomodate the weird behavior, test to
' see if LB > UB. If so, the array is not
' allocated.
''''''''''''''''''''''''''''''''''''''''''
Err.Clear
LB = LBound(Arr)
If LB > UB Then
IsArrayEmpty = True
Else
IsArrayEmpty = False
End If
End If
End Function