MacLochlainns Weblog

Michael McLaughlin's Technical Blog

Site Admin

Archive for June, 2010

Excel dynamic ranges

with 3 comments

Microsoft Excel has many Visual Basic for Application (VBA) features that are seemingly not well understood. One of these features is passing a range value into a VBA procedure (a Sub) or function. The following example demonstrates how to pass a dynamic range to a local multiple dimensional array, and process the uploaded data in a VBA function.

My sample spreadsheet looks like the screen shot below. The formula call is in cell A11 and the text of the formula is in cell B11.

I left a debug MsgBox() call that demonstrates how you size a range. This shows the range above based on zero-based numbering, which means 5 rows are reported as 4 rows because 0 contains a row, and 3 columns are reported as 2 columns for the same reason. If the dialog looks strange to a Windows user, that’s because it’s one generated on a Mac OS X running Excel 2011. 🙂

I kept this as simple as possible to demonstrate the how to do this. Unfortunately, feedback required adding more extensive comments and making it a bit more bulletproof on concepts. The variable names were chosen to help read the syntax. Two loops are used to demonstrate (a) how you assign the range values to a multidimensional array, and (b) how you read the array values in your VBA code.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62

Function dynamicArray(lookupValue As String, table As Range)
 
  ' Define the row starting cell, Row n maps to the first row where the range is found in the spreadsheet.
  ' Row 1 is the first row and 1,048,576 is the last possible row.
  Dim rowStart As Integer
  Dim rowSize As Integer
 
  ' Define the column starting cell, Column A maps to 1, Column B maps to 2, et cetera.
  ' Column A is the first column and XFD is the last possible column.
  Dim columnStart As Integer
  Dim columnSize As Integer
 
  ' Create a dynamic multiple dimension array without any physical size.
  Dim multidimensionArray As Variant
 
  ' Define and declare a local returnValue variable.
  Dim returnValue As Boolean
  returnValue = False
 
  ' Assign the starting row and column values, and the length of values.
  ' Since you need to add the row and column to the starting grid coordinates, you need to use 0-based numbering,
  ' which means you subtract one from the length.
  rowStart = table.Row
  rowSize = table.Rows.Count - 1
  columnStart = table.Column
  columnSize = table.Columns.Count - 1
 
  ' This demonstrates that the range starts in the row and column, and
  ' the length and width of the multiple dimension array.
  ' ----------------------------------------------------------------------
  ' Insert single quotes for the next two lines to suppress testing the program with variables.
  MsgBox ("(RowStart [" + CStr(rowStart) + "], (ColStart [" + CStr(columnStart) + "]) " + _
    "(RowSize [" + CStr(rowSize) + "] ColSize [" + CStr(columnSize) + "])")
  ' ----------------------------------------------------------------------
 
  ' Redimension the arrays maximum size, rows first, columns second.
  ReDim multidimensionArray(rowSize, columnSize)
 
  ' Read through the range and assign it to a local and dynamically sized array variable.
  ' An important note to those unfamilar with the Cells function, it works on the active worksheet and uses two
  ' parameters, the absolute row and column number or relative row and column numbers. In this sample, the
  ' easiest solution is to use absolute row an dolumn numbers.
  For i = 0 To rowSize
    For j = 0 To columnSize
      multidimensionArray(i, j) = CStr(Cells(rowStart + i, columnStart + j))
    Next j
  Next i
 
  ' Read through the local variable range and view the content set.
  For i = 0 To rowSize
    For j = 0 To columnSize
      ' Check if the lookupValue has been found and return true.
      If lookupValue = CStr(multidimensionArray(i, j)) Then
        returnValue = True
        Exit For
      End If
    Next j
  Next i
 
  ' Return a Boolean value: true when found and false when not found.
  dynamicArray = returnValue
End Function

You would call it with syntax like that below. The range can be any valid range value in Excel, which is any two cell references separated by a colon.

=dynamicArray("LookupString",A1:G5)

As always, I hope this helps others looking for a way to perform this task natively in Microsoft Excel. As an addendum, I thought the absence of a code example for VB on the MSDN web page was quite interesting.

Written by maclochlainn

June 2nd, 2010 at 11:53 pm

Posted in Excel 2007,Excel 2010,Excel 2011,Microsoft Excel,Microsoft Windows 7,VBA,VBA Tutorial,Windows7

Tagged with , , ,

Newer Entries »