VBA (Excel) Initialize Entire Array without Looping

Question

I am fairly new to VBA, so this may be a simple question but here goes.

I would like to initialize an entire array myArray, say of integers, in VBA. I know that I can do this by a simple initialization like so:

Dim myArray myArray = Array(1, 2, 4, 8) 

But if the array is large this is cumbersome, and I'd like to initialize all of the elements to the same value. Ideally it would be something like this:

myArray(:) = 0 

I tried that but the compiler complained. Then I tried myArray() = 0 and it complained about that, too.

Can anyone explain how to do this, without looping? I'd like to do it in one statement if possible.

Clarification:

I want to initialize every single element of the array to some initial value. So if I have an array Dim myArray(300) As Integer of 300 integers, for example, all 300 elements would hold the same initial value (say, the number 13).

More Clarification

I found this answer that states that you can do this with a variable like so:

Dim x As Double: x = 0 

Perhaps there is a way to update the syntax slightly to make it applicable to arrays?

Answer 1

This is easy, at least if you want a 1-based, 1D or 2D variant array:

Sub StuffVArr()     Dim v() As Variant     Dim q() As Variant     v = Evaluate("=IF(ISERROR(A1:K1), 13, 13)")     q = Evaluate("=IF(ISERROR(A1:G48), 13, 13)") End Sub 

Byte arrays also aren't too bad:

Private Declare Sub FillMemory Lib "kernel32" Alias "RtlFillMemory" _         (dest As Any, ByVal size As Long, ByVal fill As Byte)  Sub StuffBArr()     Dim i(0 To 39) As Byte     Dim j(1 To 2, 5 To 29, 2 To 6) As Byte     FillMemory i(0), 40, 13     FillMemory j(1, 5, 2), 2 * 25 * 5, 13 End Sub 

You can use the same method to fill arrays of other numeric data types, but you're limited to only values which can be represented with a single repeating byte:

Sub StuffNArrs()     Dim i(0 To 4) As Long     Dim j(0 To 4) As Integer     Dim u(0 To 4) As Currency     Dim f(0 To 4) As Single     Dim g(0 To 4) As Double      FillMemory i(0), 5 * LenB(i(0)), &HFF 'gives -1     FillMemory i(0), 5 * LenB(i(0)), &H80 'gives -2139062144     FillMemory i(0), 5 * LenB(i(0)), &H7F 'gives 2139062143      FillMemory j(0), 5 * LenB(j(0)), &HFF 'gives -1      FillMemory u(0), 5 * LenB(u(0)), &HFF 'gives -0.0001      FillMemory f(0), 5 * LenB(f(0)), &HFF 'gives -1.#QNAN     FillMemory f(0), 5 * LenB(f(0)), &H80 'gives -1.18e-38     FillMemory f(0), 5 * LenB(f(0)), &H7F 'gives 3.40e+38      FillMemory g(0), 5 * LenB(g(0)), &HFF 'gives -1.#QNAN End Sub 

If you want to avoid a loop in other situations, it gets even hairier. Not really worth it unless your array is 50K entries or larger. Just set each value in a loop and you'll be fast enough, as I talked about in an earlier answer.

Answer 2

You can initialize the array by specifying the dimensions. For example

Dim myArray(10) As Integer Dim myArray(1 to 10) As Integer 

If you are working with arrays and if this is your first time then I would recommend visiting Chip Pearson's WEBSITE.

What does this initialize to? For example, what if I want to initialize the entire array to 13?

When you want to initailize the array of 13 elements then you can do it in two ways

Dim myArray(12) As Integer Dim myArray(1 to 13) As Integer 

In the first the lower bound of the array would start with 0 so you can store 13 elements in array. For example

myArray(0) = 1 myArray(1) = 2 ' ' ' myArray(12) = 13 

In the second example you have specified the lower bounds as 1 so your array starts with 1 and can again store 13 values

myArray(1) = 1 myArray(2) = 2 ' ' ' myArray(13) = 13 

Wnen you initialize an array using any of the above methods, the value of each element in the array is equal to 0. To check that try this code.

Sub Sample()     Dim myArray(12) As Integer     Dim i As Integer      For i = LBound(myArray) To UBound(myArray)         Debug.Print myArray(i)     Next i End Sub 

or

Sub Sample()     Dim myArray(1 to 13) As Integer     Dim i As Integer      For i = LBound(myArray) To UBound(myArray)         Debug.Print myArray(i)     Next i End Sub 

FOLLOWUP FROM COMMENTS

So, in this example every value would be 13. So if I had an array Dim myArray(300) As Integer, all 300 elements would hold the value 13

Like I mentioned, AFAIK, there is no direct way of achieving what you want. Having said that here is one way which uses worksheet function Rept to create a repetitive string of 13's. Once we have that string, we can use SPLIT using "," as a delimiter. But note this creates a variant array but can be used in calculations.

Note also, that in the following examples myArray will actually hold 301 values of which the last one is empty - you would have to account for that by additionally initializing this value or removing the last "," from sNum before the Split operation.

Sub Sample()     Dim sNum As String     Dim i As Integer     Dim myArray      '~~> Create a string with 13 three hundred times separated by comma     '~~> 13,13,13,13...13,13 (300 times)     sNum = WorksheetFunction.Rept("13,", 300)     sNum = Left(sNum, Len(sNum) - 1)      myArray = Split(sNum, ",")      For i = LBound(myArray) To UBound(myArray)         Debug.Print myArray(i)     Next i End Sub 

Using the variant array in calculations

Sub Sample()     Dim sNum As String     Dim i As Integer     Dim myArray      '~~> Create a string with 13 three hundred times separated by comma     sNum = WorksheetFunction.Rept("13,", 300)     sNum = Left(sNum, Len(sNum) - 1)      myArray = Split(sNum, ",")      For i = LBound(myArray) To UBound(myArray)         Debug.Print Val(myArray(i)) + Val(myArray(i))     Next i End Sub