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Sorting Arrays With QSort
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Unfortunately, VBA does not have a built in sort
function. It provides no way to sort an array of strings or numeric data. This page provides a function,
QSortInPlace,
based on the QSort algorithm, that will sort an array of either string or
numeric data in either ascending or descending order. This procedure sorts
the data in place -- that is, the array variable in the calling procedure is
sorted. This function returns True if the array was successfully sorted or
False if an error occurred. If an error occurs, a message box is displayed
indicating the error. To suppress message boxes, set the NoAlerts parameter
to True. See the Passing And
Returning Arrays With Functions page for information about passing
arrays to functions and why InputArray is declared as a Variant rather than
as an array. This function can be used to sort single-dimensional arrays of simple data types (Strings, Integers, Longs, Singles, and Doubles). It will not sort arrays of user-defined types or arrays of objects. To sort arrays of objects, see the Sorting Arrays Of Objects page.
Sorting is an expensive operation, especially with large
arrays of Strings or Variants. If the possibility exists that the array is
already in sorted order, you can use the
IsArraySorted function to see if a sort is really required. 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 Here, InputArray is the array to be sorted. LB and UB indicate the Lower Bound and Upper Bound index numbers of the array elements to sort, Descending indicates whether to sort in descending order, CompareMode indicates the method used in text comparison (case sensitive or case insensitive), and NoAlerts indicates whether to suppress error message boxes. By default, QSortInPlace sorts the entire array. If you want to sort only
part of the array, set LB to the first element index number to be sorted and
set UB to the last element index number to be sorted. In this case,
only the elements between LB and UB (inclusive) will be sorted. The elements
before LB and after UB will be left in their original order. If LB is
omitted or is less than 0, it is set to the LBound of InputArray and sorting
begins at the first element of the array. If UB is omitted or is less than
0, it is set to the UBound of InputArray and sorting ends at the last
element of the array. To sort the entire array, omit the LB and UB paramters,
set both to -1, or set LB to LBound(InputArray) and set UB to
UBound(InputArray). It is up to you, the programmer, to provide a function that accepts two variables and returns the result of a comparison. The function must be called QSortCompare and should be declared as Function QSortCompare(V1 As Variant, V2 As Variant) As Long Dim ReturnValue As Long '''''''''''''''''''''''''''' ' Code to compare V1 and V2. ' ReturnValue equals: ' -1 if V1 < V2 ' 0 if V1 = V2 ' +1 if V1 > V2 '''''''''''''''''''''''''''' QSortCompare = ReturnValue End Function Substitute your own logic for the comments in the procedure above. The QSortInPlace procedure will call QSortCompare for each pair of elements in the InputArr that need to be compared. If you are using a specific data type, e.g., Longs, you change the declarations of V1 and V2 to the appropriate data type. This will make the code run faster.
Dim Arr(1 To 10) As String Optional ByVal CompareMode As
VbCompareMethod = vbTextCompare Note that if you coerce InputArray to a ByVal argument, the procedure will not work. The
QSortInPlace
procedure requires the following procedures, which are included in the code
below and in the downloadable bas file: You can download the bas code module with these procedures here. Option Explicit Option Compare Text ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' modQSortInPlace ' By Chip Pearson, www.cpearson.com, chip@cpearson.com ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' This module contains the QSortInPlace procedure and private supporting procedures. ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 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." RecursionLevel = RecursionLevel - 1 End If 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 CurMidpoint = (LB + UB) \ 2 ' note integer division (\) here 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 ReverseArrayInPlace InputArray End If End If RecursionLevel = RecursionLevel - 1 QSortInPlace = True End Function Private 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 Private 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 Private 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 '''''''''''''''''''''''''''''''' ' 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 Ndx2 = UBound(InputArray) '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' loop from the LBound of InputArray to the midpoint of InputArray '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' For Ndx = LBound(InputArray) To ((UBound(InputArray) - LBound(InputArray) + 1) \ 2) ''''''''''''''''''''''''''''''''' 'swap the elements ''''''''''''''''''''''''''''''''' Temp = InputArray(Ndx) InputArray(Ndx) = InputArray(Ndx2) InputArray(Ndx2) = Temp ''''''''''''''''''''''''''''' ' decrement the upper index ''''''''''''''''''''''''''''' Ndx2 = Ndx2 - 1 Next Ndx ReverseArrayInPlace = True End Function Private 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 Private 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 Private 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
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Created By Chip Pearson and
Pearson Software Consulting, LLC
This Page:
Updated: November 06, 2013
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