ThreeWave Sorting Array In VBA

This page describes procedures for sorting arrays of values in VBA.
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Introduction

The VBA language has no support for sorting the values stored in an array. One method that can be used to sort arrays is to put the data on to a worksheet, sort the data on the worksheet, and then read back the values from the worksheet into the array. The other method for sorting arrays is to use the QSort algorithm to sort the array in place. This page describes both methods, with variations on the QSort method.

Sorting Via Worksheet

This section describes code that uses Excel's range sorting method to sort the values in an array. The code first creates a new worksheet so that this code won't clash with existing data on a worksheet. Then, it loads the values in the array to a range on the new worksheet, begining in cell A1. That range is sorted and the data is read back into the array in VBA. The code for SortViaWorksheet is shown below.

Sub SortViaWorksheet()
    Dim Arr(1 To 5) As String ' this is the array to be sorted
    Dim WS As Worksheet ' temporary worksheet
    Dim R As Range
    Dim N As Long
    
    ' fill up the array with some
    ' aribtrary values.
    Arr(1) = "aaa"
    Arr(2) = "zzz"
    Arr(3) = "mmm"
    Arr(4) = "ttt"
    Arr(5) = "bbb"
    
    Application.ScreenUpdating = False
    
    ' create a new sheet
    Set WS = ThisWorkbook.Worksheets.Add
    
    ' put the array values on the worksheet
    Set R = WS.Range("A1").Resize(UBound(Arr) - LBound(Arr) + 1, 1)
    R = Application.Transpose(Arr)
    
    ' sort the range
    R.Sort key1:=R, order1:=xlAscending, MatchCase:=False
    
    ' load the worksheet values back into the array
    For N = 1 To R.Rows.Count
        Arr(N) = R(N, 1)
    Next N
    
    ' delete the temporary sheet
    Application.DisplayAlerts = False
    WS.Delete
    Application.DisplayAlerts = True
    Application.ScreenUpdating = True
    
    ' test/debug/confirmation
    For N = LBound(Arr) To UBound(Arr)
        Debug.Print Arr(N)
    Next N   
End Sub

The SortViaWorksheet function works if you are using Excel and the structure of the workbook is not protected. It the workbook is protected, you'll get an error when creating the new sheet, so you will have to have a scratch sheet in place beforehand or use an unused region of an existing (and unprotected) worksheet. Due to these limitations, coupled with the fact that VBA is used in many applications other than Excel, it may be desirable to employ a VBA-only method that doesn't rely on any outside objects.

Sorting by any method is an expensive operations, especially with large arrays, due to the number of swaps made during the sorting process. Before sorting a large array, it might be useful to test whether the array is already in sorted order and thus does not need to be sorted. Procedures for testing if an array is sorted can be found on the IsArraySorted page.

Sorting With VBA Code

The code below in a implementation of the QSort algorithm for sorting an array. It will work with array that contain either numeric or string values. The input array is sorted in place. That means that after the procedure has ended, the original array will have been modified and sorted. The QSortInPlace and related procedures will sort an array of numeric or string values in either ascending or descending order. The declaration for QSortInPlace is shown below:

Public Function QSortInPlace( _
    ByRef InputArray As Variant, _
    Optional ByVal LB As Long = -1&, _
    Optional ByVal UB As Long = -1&, _
    Optional ByVal Descending As Boolean = False, _
    Optional ByVal CompareMode As VbCompareMethod = vbTextCompare, _
    Optional ByVal NoAlerts As Boolean = False) As Boolean

InputArray is the array to be sorted. LB is the first element of the input array to sort. A value of -1 indicates to start sorting with the first element. UB is the last element of the input array to sort. A value of -1 indicates to sort to the end of the array. By modifying the values of LB and UB, you can sort only a subset of the array. Descending, if False or omitted, causes the sort to progress in ascending order. If Descending is True, the array is sorted in descending order. CompareMode indicates whether the sorting is case sensitive or case insensitive. NoAlerts if True, supresses error messages that may occur. The function returns True if the sort was successful or False if an error occurred. There are several procedures that support the QSortInPlace function, so you should import the entire module into your project.

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The Code

The code for QSortInPlace and supporting procedures is shown below:


Public Function QSortInPlace( _
    ByRef InputArray As Variant, _
    Optional ByVal LB As Long = -1&, _
    Optional ByVal UB As Long = -1&, _
    Optional ByVal Descending As Boolean = False, _
    Optional ByVal CompareMode As VbCompareMethod = vbTextCompare, _
    Optional ByVal NoAlerts As Boolean = False) As Boolean
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' QSortInPlace
'
' This function sorts the array InputArray in place -- this is, the original array in the
' calling procedure is sorted. It will work with either string data or numeric data.
' It need not sort the entire array. You can sort only part of the array by setting the LB and
' UB parameters to the first (LB) and last (UB) element indexes that you want to sort.
' LB and UB are optional parameters. If omitted LB is set to the LBound of InputArray, and if
' omitted UB is set to the UBound of the InputArray. If you want to sort the entire array,
' omit the LB and UB parameters, or set both to -1, or set LB = LBound(InputArray) and set
' UB to UBound(InputArray).
'
' By default, the sort method is case INSENSTIVE (case doens't matter: "A", "b", "C", "d").
' To make it case SENSITIVE (case matters: "A" "C" "b" "d"), set the CompareMode argument
' to vbBinaryCompare (=0). If Compare mode is omitted or is any value other than vbBinaryCompare,
' it is assumed to be vbTextCompare and the sorting is done case INSENSITIVE.
'
' The function returns TRUE if the array was successfully sorted or FALSE if an error
' occurred. If an error occurs (e.g., LB > UB), a message box indicating the error is
' displayed. To suppress message boxes, set the NoAlerts parameter to TRUE.
'
''''''''''''''''''''''''''''''''''''''
' MODIFYING THIS CODE:
''''''''''''''''''''''''''''''''''''''
' If you modify this code and you call "Exit Procedure", you MUST decrment the RecursionLevel
' variable. E.g.,
'       If SomethingThatCausesAnExit Then
'           RecursionLevel = RecursionLevel - 1
'           Exit Function
'       End If
'''''''''''''''''''''''''''''''''''''''
'
' Note: If you coerce InputArray to a ByVal argument, QSortInPlace will not be
' able to reference the InputArray in the calling procedure and the array will
' not be sorted.
'
' This function uses the following procedures. These are declared as Private procedures
' at the end of this module:
'       IsArrayAllocated
'       IsSimpleDataType
'       IsSimpleNumericType
'       QSortCompare
'       NumberOfArrayDimensions
'       ReverseArrayInPlace
'
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

Dim Temp As Variant
Dim Buffer As Variant
Dim CurLow As Long
Dim CurHigh As Long
Dim CurMidpoint As Long
Dim Ndx As Long
Dim pCompareMode As VbCompareMethod

'''''''''''''''''''''''''
' Set the default result.
'''''''''''''''''''''''''
QSortInPlace = False

''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' This variable is used to determine the level
' of recursion  (the function calling itself).
' RecursionLevel is incremented when this procedure
' is called, either initially by a calling procedure
' or recursively by itself. The variable is decremented
' when the procedure exits. We do the input parameter
' validation only when RecursionLevel is 1 (when
' the function is called by another function, not
' when it is called recursively).
''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Static RecursionLevel As Long


''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Keep track of the recursion level -- that is, how many
' times the procedure has called itself.
' Carry out the validation routines only when this
' procedure is first called. Don't run the
' validations on a recursive call to the
' procedure.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
RecursionLevel = RecursionLevel + 1

If RecursionLevel = 1 Then
    ''''''''''''''''''''''''''''''''''
    ' Ensure InputArray is an array.
    ''''''''''''''''''''''''''''''''''
    If IsArray(InputArray) = False Then
        If NoAlerts = False Then
            MsgBox "The InputArray parameter is not an array."
        End If
        '''''''''''''''''''''''''''''''''''''''''''''''''''''''
        ' InputArray is not an array. Exit with a False result.
        '''''''''''''''''''''''''''''''''''''''''''''''''''''''
        RecursionLevel = RecursionLevel - 1
        Exit Function
    End If
    
    ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
    ' Test LB and UB. If < 0 then set to LBound and UBound
    ' of the InputArray.
    ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
    If LB < 0 Then
        LB = LBound(InputArray)
    End If
    If UB < 0 Then
        UB = UBound(InputArray)
    End If
    
    Select Case NumberOfArrayDimensions(InputArray)
        Case 0
            ''''''''''''''''''''''''''''''''''''''''''
            ' Zero dimensions indicates an unallocated
            ' dynamic array.
            ''''''''''''''''''''''''''''''''''''''''''
            If NoAlerts = False Then
                MsgBox "The InputArray is an empty, unallocated array."
            End If
            RecursionLevel = RecursionLevel - 1
            Exit Function
        Case 1
            ''''''''''''''''''''''''''''''''''''''''''
            ' We sort ONLY single dimensional arrays.
            ''''''''''''''''''''''''''''''''''''''''''
        Case Else
            ''''''''''''''''''''''''''''''''''''''''''
            ' We sort ONLY single dimensional arrays.
            ''''''''''''''''''''''''''''''''''''''''''
            If NoAlerts = False Then
                MsgBox "The InputArray is multi-dimensional." & _
                      "QSortInPlace works only on single-dimensional arrays."
            End If
            RecursionLevel = RecursionLevel - 1
            Exit Function
    End Select
    '''''''''''''''''''''''''''''''''''''''''''''''''''
    ' Ensure that InputArray is an array of simple data
    ' types, not other arrays or objects. This tests
    ' the data type of only the first element of
    ' InputArray. If InputArray is an array of Variants,
    ' subsequent data types may not be simple data types
    ' (e.g., they may be objects or other arrays), and
    ' this may cause QSortInPlace to fail on the StrComp
    ' operation.
    '''''''''''''''''''''''''''''''''''''''''''''''''''
    If IsSimpleDataType(InputArray(LBound(InputArray))) = False Then
        If NoAlerts = False Then
            MsgBox "InputArray is not an array of simple data types."
            RecursionLevel = RecursionLevel - 1
            Exit Function
        End If
    End If
    ''''''''''''''''''''''''''''''''''''''''''''''''''''
    ' ensure that the LB parameter is valid.
    ''''''''''''''''''''''''''''''''''''''''''''''''''''
    Select Case LB
        Case Is < LBound(InputArray)
            If NoAlerts = False Then
                MsgBox "The LB lower bound parameter is less than the LBound of the InputArray"
            End If
            RecursionLevel = RecursionLevel - 1
            Exit Function
        Case Is > UBound(InputArray)
            If NoAlerts = False Then
                MsgBox "The LB lower bound parameter is greater than the UBound of the InputArray"
            End If
            RecursionLevel = RecursionLevel - 1
            Exit Function
        Case Is > UB
            If NoAlerts = False Then
                MsgBox "The LB lower bound parameter is greater than the UB upper bound parameter."
            End If
            RecursionLevel = RecursionLevel - 1
            Exit Function
    End Select

    ''''''''''''''''''''''''''''''''''''''''''''''''''''
    ' ensure the UB parameter is valid.
    ''''''''''''''''''''''''''''''''''''''''''''''''''''
    Select Case UB
        Case Is > UBound(InputArray)
            If NoAlerts = False Then
                MsgBox "The UB upper bound parameter is greater than the upper bound of the InputArray."
            End If
            RecursionLevel = RecursionLevel - 1
            Exit Function
        Case Is < LBound(InputArray)
            If NoAlerts = False Then
                MsgBox "The UB upper bound parameter is less than the lower bound of the InputArray."
            End If
            RecursionLevel = RecursionLevel - 1
            Exit Function
        Case Is < LB
            If NoAlerts = False Then
                MsgBox "the UB upper bound parameter is less than the LB lower bound parameter."
            End If
            RecursionLevel = RecursionLevel - 1
            Exit Function
    End Select

    ''''''''''''''''''''''''''''''''''''''''''''''''''''''
    ' if UB = LB, we have nothing to sort, so get out.
    ''''''''''''''''''''''''''''''''''''''''''''''''''''''
    If UB = LB Then
        QSortInPlace = True
        RecursionLevel = RecursionLevel - 1
        Exit Function
    End If

End If ' RecursionLevel = 1

''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Ensure that CompareMode is either vbBinaryCompare  or
' vbTextCompare. If it is neither, default to vbTextCompare.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
If (CompareMode = vbBinaryCompare) Or (CompareMode = vbTextCompare) Then
    pCompareMode = CompareMode
Else
    pCompareMode = vbTextCompare
End If

''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Begin the actual sorting process.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
CurLow = LB
CurHigh = UB

If LB = 0 Then
    CurMidpoint = ((LB + UB) \ 2) + 1
Else
    CurMidpoint = (LB + UB) \ 2 ' note integer division (\) here
End If
Temp = InputArray(CurMidpoint)

Do While (CurLow <= CurHigh)
    
    Do While QSortCompare(V1:=InputArray(CurLow), V2:=Temp, CompareMode:=pCompareMode) < 0
        CurLow = CurLow + 1
        If CurLow = UB Then
            Exit Do
        End If
    Loop
    
    Do While QSortCompare(V1:=Temp, V2:=InputArray(CurHigh), CompareMode:=pCompareMode) < 0
        CurHigh = CurHigh - 1
        If CurHigh = LB Then
           Exit Do
        End If
    Loop

    If (CurLow <= CurHigh) Then
        Buffer = InputArray(CurLow)
        InputArray(CurLow) = InputArray(CurHigh)
        InputArray(CurHigh) = Buffer
        CurLow = CurLow + 1
        CurHigh = CurHigh - 1
    End If
Loop

If LB < CurHigh Then
    QSortInPlace InputArray:=InputArray, LB:=LB, UB:=CurHigh, _
        Descending:=Descending, CompareMode:=pCompareMode, NoAlerts:=True
End If

If CurLow < UB Then
    QSortInPlace InputArray:=InputArray, LB:=CurLow, UB:=UB, _
        Descending:=Descending, CompareMode:=pCompareMode, NoAlerts:=True
End If

'''''''''''''''''''''''''''''''''''''
' If Descending is True, reverse the
' order of the array, but only if the
' recursion level is 1.
'''''''''''''''''''''''''''''''''''''
If Descending = True Then
    If RecursionLevel = 1 Then
        ReverseArrayInPlace2 InputArray, LB, UB
    End If
End If

RecursionLevel = RecursionLevel - 1
QSortInPlace = True
End Function

Public Function QSortCompare(V1 As Variant, V2 As Variant, _
    Optional CompareMode As VbCompareMethod = vbTextCompare) As Long
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' QSortCompare
' This function is used in QSortInPlace to compare two elements. If
' V1 AND V2 are both numeric data types (integer, long, single, double)
' they are converted to Doubles and compared. If V1 and V2 are BOTH strings
' that contain numeric data, they are converted to Doubles and compared.
' If either V1 or V2 is a string and does NOT contain numeric data, both
' V1 and V2 are converted to Strings and compared with StrComp.
'
' The result is -1 if V1 < V2,
'                0 if V1 = V2
'                1 if V1 > V2
' For text comparisons, case sensitivity is controlled by CompareMode.
' If this is vbBinaryCompare, the result is case SENSITIVE. If this
' is omitted or any other value, the result is case INSENSITIVE.
'
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Dim D1 As Double
Dim D2 As Double
Dim S1 As String
Dim S2 As String

Dim Compare As VbCompareMethod
''''''''''''''''''''''''''''''''''''''''''''''''
' Test CompareMode. Any value other than
' vbBinaryCompare will default to vbTextCompare.
''''''''''''''''''''''''''''''''''''''''''''''''
If CompareMode = vbBinaryCompare Or CompareMode = vbTextCompare Then
    Compare = CompareMode
Else
    Compare = vbTextCompare
End If
'''''''''''''''''''''''''''''''''''''''''''''''
' If either V1 or V2 is either an array or
' an Object, raise a error 13 - Type Mismatch.
'''''''''''''''''''''''''''''''''''''''''''''''
If IsArray(V1) = True Or IsArray(V2) = True Then
    Err.Raise 13
    Exit Function
End If
If IsObject(V1) = True Or IsObject(V2) = True Then
    Err.Raise 13
    Exit Function
End If

If IsSimpleNumericType(V1) = True Then
    If IsSimpleNumericType(V2) = True Then
        '''''''''''''''''''''''''''''''''''''
        ' If BOTH V1 and V2 are numeric data
        ' types, then convert to Doubles and
        ' do an arithmetic compare and
        ' return the result.
        '''''''''''''''''''''''''''''''''''''
        D1 = CDbl(V1)
        D2 = CDbl(V2)
        If D1 = D2 Then
            QSortCompare = 0
            Exit Function
        End If
        If D1 < D2 Then
            QSortCompare = -1
            Exit Function
        End If
        If D1 > D2 Then
            QSortCompare = 1
            Exit Function
        End If
    End If
End If
''''''''''''''''''''''''''''''''''''''''''''
' Either V1 or V2 was not numeric data type.
' Test whether BOTH V1 AND V2 are numeric
' strings. If BOTH are numeric, convert to
' Doubles and do a arithmetic comparison.
''''''''''''''''''''''''''''''''''''''''''''
If IsNumeric(V1) = True And IsNumeric(V2) = True Then
    D1 = CDbl(V1)
    D2 = CDbl(V2)
    If D1 = D2 Then
        QSortCompare = 0
        Exit Function
    End If
    If D1 < D2 Then
        QSortCompare = -1
        Exit Function
    End If
    If D1 > D2 Then
        QSortCompare = 1
        Exit Function
    End If
End If
''''''''''''''''''''''''''''''''''''''''''''''
' Either or both V1 and V2 was not numeric
' string. In this case, convert to Strings
' and use StrComp to compare.
''''''''''''''''''''''''''''''''''''''''''''''
S1 = CStr(V1)
S2 = CStr(V2)
QSortCompare = StrComp(S1, S2, Compare)

End Function

Public Function NumberOfArrayDimensions(Arr As Variant) As Integer
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' NumberOfArrayDimensions
' This function returns the number of dimensions of an array. An unallocated dynamic array
' has 0 dimensions. This condition can also be tested with IsArrayEmpty.
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Dim Ndx As Integer
Dim Res As Integer
On Error Resume Next
' Loop, increasing the dimension index Ndx, until an error occurs.
' An error will occur when Ndx exceeds the number of dimension
' in the array. Return Ndx - 1.
Do
    Ndx = Ndx + 1
    Res = UBound(Arr, Ndx)
Loop Until Err.Number <> 0

NumberOfArrayDimensions = Ndx - 1

End Function


Public Function ReverseArrayInPlace(InputArray As Variant, _
    Optional NoAlerts As Boolean = False) As Boolean
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' ReverseArrayInPlace
' This procedure reverses the order of an array in place -- this is, the array variable
' in the calling procedure is sorted. An error will occur if InputArray is not an array,
 'if it is an empty, unallocated array, or if the number of dimensions is not 1.
'
' NOTE: Before calling the ReverseArrayInPlace procedure, consider if your needs can
' be met by simply reading the existing array in reverse order (Step -1). If so, you can save
' the overhead added to your application by calling this function.
'
' The function returns TRUE if the array was successfully reversed, or FALSE if
' an error occurred.
'
' If an error occurred, a message box is displayed indicating the error. To suppress
' the message box and simply return FALSE, set the NoAlerts parameter to TRUE.
'
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Dim Temp As Variant
Dim Ndx As Long
Dim Ndx2 As Long
Dim OrigN As Long
Dim NewN As Long
Dim NewArr() As Variant

''''''''''''''''''''''''''''''''
' Set the default return value.
''''''''''''''''''''''''''''''''
ReverseArrayInPlace = False

'''''''''''''''''''''''''''''''''
' Ensure we have an array
'''''''''''''''''''''''''''''''''
If IsArray(InputArray) = False Then
   If NoAlerts = False Then
        MsgBox "The InputArray parameter is not an array."
    End If
    Exit Function
End If

''''''''''''''''''''''''''''''''''''''
' Test the number of dimensions of the
' InputArray. If 0, we have an empty,
' unallocated array. Get out with
' an error message. If greater than
' one, we have a multi-dimensional
' array, which is not allowed. Only
' an allocated 1-dimensional array is
' allowed.
''''''''''''''''''''''''''''''''''''''
Select Case NumberOfArrayDimensions(InputArray)
    Case 0
        '''''''''''''''''''''''''''''''''''''''''''
        ' Zero dimensions indicates an unallocated
        ' dynamic array.
        '''''''''''''''''''''''''''''''''''''''''''
        If NoAlerts = False Then
            MsgBox "The input array is an empty, unallocated array."
        End If
        Exit Function
    Case 1
        '''''''''''''''''''''''''''''''''''''''''''
        ' We can reverse ONLY a single dimensional
        ' arrray.
        '''''''''''''''''''''''''''''''''''''''''''
    Case Else
        '''''''''''''''''''''''''''''''''''''''''''
        ' We can reverse ONLY a single dimensional
        ' arrray.
        '''''''''''''''''''''''''''''''''''''''''''
        If NoAlerts = False Then
            MsgBox "The input array multi-dimensional. ReverseArrayInPlace works only " & _
                   "on single-dimensional arrays."
        End If
        Exit Function

End Select

'''''''''''''''''''''''''''''''''''''''''''''
' Ensure that we have only simple data types,
' not an array of objects or arrays.
'''''''''''''''''''''''''''''''''''''''''''''
If IsSimpleDataType(InputArray(LBound(InputArray))) = False Then
    If NoAlerts = False Then
        MsgBox "The input array contains arrays, objects, or other complex data types." & vbCrLf & _
            "ReverseArrayInPlace can reverse only arrays of simple data types."
        Exit Function
    End If
End If

ReDim NewArr(LBound(InputArray) To UBound(InputArray))
NewN = UBound(NewArr)
For OrigN = LBound(InputArray) To UBound(InputArray)
    NewArr(NewN) = InputArray(OrigN)
    NewN = NewN - 1
Next OrigN

For NewN = LBound(NewArr) To UBound(NewArr)
    InputArray(NewN) = NewArr(NewN)
Next NewN

ReverseArrayInPlace = True
End Function


Public Function ReverseArrayInPlace2(InputArray As Variant, _
    Optional LB As Long = -1, Optional UB As Long = -1, _
    Optional NoAlerts As Boolean = False) As Boolean
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' ReverseArrayInPlace2
' This reverses the order of elements in InputArray. To reverse the entire array, omit or
' set to less than 0 the LB and UB parameters. To reverse only part of tbe array, set LB and/or
' UB to the LBound and UBound of the sub array to be reversed.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Dim N As Long
Dim Temp As Variant
Dim Ndx As Long
Dim Ndx2 As Long
Dim OrigN As Long
Dim NewN As Long
Dim NewArr() As Variant

''''''''''''''''''''''''''''''''
' Set the default return value.
''''''''''''''''''''''''''''''''
ReverseArrayInPlace2 = False

'''''''''''''''''''''''''''''''''
' Ensure we have an array
'''''''''''''''''''''''''''''''''
If IsArray(InputArray) = False Then
    If NoAlerts = False Then
        MsgBox "The InputArray parameter is not an array."
    End If
    Exit Function
End If

''''''''''''''''''''''''''''''''''''''
' Test the number of dimensions of the
' InputArray. If 0, we have an empty,
' unallocated array. Get out with
' an error message. If greater than
' one, we have a multi-dimensional
' array, which is not allowed. Only
' an allocated 1-dimensional array is
' allowed.
''''''''''''''''''''''''''''''''''''''
Select Case NumberOfArrayDimensions(InputArray)
    Case 0
        '''''''''''''''''''''''''''''''''''''''''''
        ' Zero dimensions indicates an unallocated
        ' dynamic array.
        '''''''''''''''''''''''''''''''''''''''''''
        If NoAlerts = False Then
            MsgBox "The input array is an empty, unallocated array."
        End If
        Exit Function
    Case 1
        '''''''''''''''''''''''''''''''''''''''''''
        ' We can reverse ONLY a single dimensional
        ' arrray.
        '''''''''''''''''''''''''''''''''''''''''''
    Case Else
        '''''''''''''''''''''''''''''''''''''''''''
        ' We can reverse ONLY a single dimensional
        ' arrray.
        '''''''''''''''''''''''''''''''''''''''''''
        If NoAlerts = False Then
            MsgBox "The input array multi-dimensional. ReverseArrayInPlace works only " & _
                   "on single-dimensional arrays."
        End If
        Exit Function

End Select

'''''''''''''''''''''''''''''''''''''''''''''
' Ensure that we have only simple data types,
' not an array of objects or arrays.
'''''''''''''''''''''''''''''''''''''''''''''
If IsSimpleDataType(InputArray(LBound(InputArray))) = False Then
    If NoAlerts = False Then
        MsgBox "The input array contains arrays, objects, or other complex data types." & vbCrLf & _
            "ReverseArrayInPlace can reverse only arrays of simple data types."
        Exit Function
    End If
End If

If LB < 0 Then
    LB = LBound(InputArray)
End If
If UB < 0 Then
    UB = UBound(InputArray)
End If

For N = LB To (LB + ((UB - LB - 1) \ 2))
    Temp = InputArray(N)
    InputArray(N) = InputArray(UB - (N - LB))
    InputArray(UB - (N - LB)) = Temp
Next N

ReverseArrayInPlace2 = True
End Function


Public Function IsSimpleNumericType(V As Variant) As Boolean
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' IsSimpleNumericType
' This returns TRUE if V is one of the following data types:
'        vbBoolean
'        vbByte
'        vbCurrency
'        vbDate
'        vbDecimal
'        vbDouble
'        vbInteger
'        vbLong
'        vbSingle
'        vbVariant if it contains a numeric value
' It returns FALSE for any other data type, including any array
' or vbEmpty.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
If IsSimpleDataType(V) = True Then
    Select Case VarType(V)
        Case vbBoolean, _
                vbByte, _
                vbCurrency, _
                vbDate, _
                vbDecimal, _
                vbDouble, _
                vbInteger, _
                vbLong, _
                vbSingle
            IsSimpleNumericType = True
        Case vbVariant
            If IsNumeric(V) = True Then
                IsSimpleNumericType = True
            Else
                IsSimpleNumericType = False
            End If
        Case Else
            IsSimpleNumericType = False
    End Select
Else
    IsSimpleNumericType = False
End If
End Function

Public Function IsSimpleDataType(V As Variant) As Boolean
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' IsSimpleDataType
' This function returns TRUE if V is one of the following
' variable types (as returned by the VarType function:
'    vbBoolean
'    vbByte
'    vbCurrency
'    vbDate
'    vbDecimal
'    vbDouble
'    vbEmpty
'    vbError
'    vbInteger
'    vbLong
'    vbNull
'    vbSingle
'    vbString
'    vbVariant
'
' It returns FALSE if V is any one of the following variable
' types:
'    vbArray
'    vbDataObject
'    vbObject
'    vbUserDefinedType
'    or if it is an array of any type.

''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
On Error Resume Next
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Test if V is an array. We can't just use VarType(V) = vbArray
' because the VarType of an array is vbArray + VarType(type
' of array element). E.g, the VarType of an Array of Longs is
' 8195 = vbArray + vbLong.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
If IsArray(V) = True Then
    IsSimpleDataType = False
    Exit Function
End If
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' We must also explicitly check whether V is an object, rather
' relying on VarType(V) to equal vbObject. The reason is that
' if V is an object and that object has a default proprety, VarType
' returns the data type of the default property. For example, if
' V is an Excel.Range object pointing to cell A1, and A1 contains
' 12345, VarType(V) would return vbDouble, the since Value is
' the default property of an Excel.Range object and the default
' numeric type of Value in Excel is Double. Thus, in order to
' prevent this type of behavior with default properties, we test
' IsObject(V) to see if V is an object.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
If IsObject(V) = True Then
    IsSimpleDataType = False
    Exit Function
End If
'''''''''''''''''''''''''''''''''''''
' Test the value returned by VarType.
'''''''''''''''''''''''''''''''''''''
Select Case VarType(V)
    Case vbArray, vbDataObject, vbObject, vbUserDefinedType
        '''''''''''''''''''''''
        ' not simple data types
        '''''''''''''''''''''''
        IsSimpleDataType = False
    Case Else
        ''''''''''''''''''''''''''''''''''''
        ' otherwise it is a simple data type
        ''''''''''''''''''''''''''''''''''''
        IsSimpleDataType = True
End Select

End Function

Public Function IsArrayAllocated(Arr As Variant) As Boolean
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' IsArrayAllocated
' Returns TRUE if the array is allocated (either a static array or a dynamic array that has been
' sized with Redim) or FALSE if the array has not been allocated (a dynamic that has not yet
' been sized with Redim, or a dynamic array that has been Erased).
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

Dim N As Long

'''''''''''''''''''''''''''''''''''''''''''''''''''
' If Arr is not an array, return FALSE and get out.
'''''''''''''''''''''''''''''''''''''''''''''''''''
If IsArray(Arr) = False Then
    IsArrayAllocated = False
    Exit Function
End If

''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Try to get the UBound of the array. If the array has not been allocated,
' an error will occur. Test Err.Number to see if an error occured.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
On Error Resume Next
N = UBound(Arr, 1)
If Err.Number = 0 Then
    '''''''''''''''''''''''''''''''''''''
    ' No error. Array has been allocated.
    '''''''''''''''''''''''''''''''''''''
    IsArrayAllocated = True
Else
    '''''''''''''''''''''''''''''''''''''
    ' Error. Unallocated array.
    '''''''''''''''''''''''''''''''''''''
    IsArrayAllocated = False
End If

End Function
download You can download the file with all the example code on this page.
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LastUpdate This page last updated: 7-June-2009.