How do I declare an array variable in VBA? - arrays

I need to add the var in array
Public Sub Testprog()
Dim test As Variant
Dim iCounter As Integer
If test = Empty Then
iCounter = 0
test(iCounter) = "test"
Else
iCounter = UBound(test)
End If
End Sub
Getting error at test(iCounter) = "test"
Please suggest some solution

Generally, you should declare variables of a specific type, rather than Variant. In this example, the test variable should be of type String.
And, because it's an array, you need to indicate that specifically when you declare the variable. There are two ways of declaring array variables:
If you know the size of the array (the number of elements that it should contain) when you write the program, you can specify that number in parentheses in the declaration:
Dim test(1) As String 'declares an array with 2 elements that holds strings
This type of array is referred to as a static array, as its size is fixed, or static.
If you do not know the size of the array when you write the application, you can use a dynamic array. A dynamic array is one whose size is not specified in the declaration (Dim statement), but rather is determined later during the execution of the program using the ReDim statement. For example:
Dim test() As String
Dim arraySize As Integer
' Code to do other things, like calculate the size required for the array
' ...
arraySize = 5
ReDim test(arraySize) 'size the array to the value of the arraySize variable

Further to Cody Gray's answer, there's a third way (everything there applies her as well):
You can also use a dynamic array that's resized on the fly:
Dim test() as String
Dim arraySize as Integer
Do While someCondition
'...whatever
arraySize = arraySize + 1
ReDim Preserve test(arraySize)
test(arraySize) = newStringValue
Loop
Note the Preserve keyword. Without it, redimensioning an array also initializes all the elements.

Further to RolandTumble's answer to Cody Gray's answer, both fine answers, here is another very simple and flexible way, when you know all of the array contents at coding time - e.g. you just want to build an array that contains 1, 10, 20 and 50. This also uses variant declaration, but doesn't use ReDim. Like in Roland's answer, the enumerated count of the number of array elements need not be specifically known, but is obtainable by using uBound.
sub Demo_array()
Dim MyArray as Variant, MyArray2 as Variant, i as Long
MyArray = Array(1, 10, 20, 50) 'The key - the powerful Array() statement
MyArray2 = Array("Apple", "Pear", "Orange") 'strings work too
For i = 0 to UBound(MyArray)
Debug.Print i, MyArray(i)
Next i
For i = 0 to UBound(MyArray2)
Debug.Print i, MyArray2(i)
Next i
End Sub
I love this more than any of the other ways to create arrays. What's great is that you can add or subtract members of the array right there in the Array statement, and nothing else need be done to code. To add Egg to your 3 element food array, you just type
, "Egg"
in the appropriate place, and you're done. Your food array now has the 4 elements, and nothing had to be modified in the Dim, and ReDim is omitted entirely.
If a 0-based array is not desired - i.e., using MyArray(0) - one solution is just to jam a 0 or "" for that first element.
Note, this might be regarded badly by some coding purists; one fair objection would be that "hard data" should be in Const statements, not code statements in routines. Another beef might be that, if you stick 36 elements into an array, you should set a const to 36, rather than code in ignorance of that. The latter objection is debatable, because it imposes a requirement to maintain the Const with 36 rather than relying on uBound. If you add a 37th element but leave the Const at 36, trouble is possible.

As pointed out by others, your problem is that you have not declared an array
Below I've tried to recreate your program so that it works as you intended.
I tried to leave as much as possible as it was (such as leaving your array as a variant)
Public Sub Testprog()
'"test()" is an array, "test" is not
Dim test() As Variant
'I am assuming that iCounter is the array size
Dim iCounter As Integer
'"On Error Resume Next" just makes us skip over a section that throws the error
On Error Resume Next
'if test() has not been assigned a UBound or LBound yet, calling either will throw an error
' without an LBound and UBound an array won't hold anything (we will assign them later)
'Array size can be determined by (UBound(test) - LBound(test)) + 1
If (UBound(test) - LBound(test)) + 1 > 0 Then
iCounter = (UBound(test) - LBound(test)) + 1
'So that we don't run the code that deals with UBound(test) throwing an error
Exit Sub
End If
'All the code below here will run if UBound(test)/LBound(test) threw an error
iCounter = 0
'This makes LBound(test) = 0
' and UBound(test) = iCounter where iCounter is 0
' Which gives us one element at test(0)
ReDim Preserve test(0 To iCounter)
test(iCounter) = "test"
End Sub

You have to declare the array variable as an array:
Dim test(10) As Variant

David, Error comes Microsoft Office Excel has stopped working. Two options check online for a solution and close the programme and other option Close the program
I am sure error is in my array but I am reading everything and seem this is way to define arrays.

The Array index only accepts a long value.
You declared iCounter as an integer. You should declare it as a long.

Related

Add Strings to Dynamic Array VBA

Problem: I am comparing two columns of names. If a name from the primary column matches a name in the secondary column, then I would like to add the matching name to an array of strings.
Function 1: This boolean function should indicate whether there is a match:
Function Match(name As String, s As Worksheet, column As Integer) As Boolean
Dim i As Integer
i = 2
While s.Cells(i, column) <> ""
If s.Cells(i, column).Value = name Then
Match = True
End If
i = i + 1
Wend
Match = False
End Function
Function 2: This function should add the matching name to a dynamic array of strings. Here I am somewhat stuck as I am new to arrays- any suggestions?
Function AddToArray(ys) As String()
Dim a() As String
Dim size As Integer
Dim i As Integer
Dim sh As Worksheet
Dim rw As Range
size = 0
ReDim Preserve a(size)
For Each rw In sh.Rows
If Match(sh.Cells(rw.Row, 1), s, column) = True Then
??
size = size + 1
End Function
Here is one solution. I scrapped your Match function and replaced it with a Find function.
Option Explicit
Sub AddToArray()
Dim primaryColumn As Range, secondaryColumn As Range, matchedRange As Range
Dim i As Long, currentIndex As Long
Dim matchingNames As Variant
With ThisWorkbook.Worksheets("Sheet1")
Set primaryColumn = .Range("A1:A10")
Set secondaryColumn = .Range("B1:B10")
End With
'Size your array so no dynamic resizing is necessary
ReDim matchingNames(1 To primaryColumn.Rows.Count)
currentIndex = 1
'loop through your primary column
'add any values that match to the matchingNames array
For i = 1 To primaryColumn.Rows.Count
On Error Resume Next
Set matchedRange = secondaryColumn.Find(primaryColumn.Cells(i, 1).Value)
On Error GoTo 0
If Not matchedRange Is Nothing Then
matchingNames(currentIndex) = matchedRange.Value
currentIndex = currentIndex + 1
End If
Next i
'remove unused part of array
ReDim Preserve matchingNames(1 To currentIndex - 1)
'matchingNames array now contains just the values you want... use it how you need!
Debug.Print matchingNames(1)
Debug.Print matchingNames(2)
'...etc
End Sub
Extra comments
There is no need to create your own Match function because it already exists in VBA:
Application.Match()
WorksheetFunction.Match()
and as I mentioned above you can also achieve the same result with the Find function which is my preference here because I prefer the way you can check for no matches (other methods throw less convenient errors).
Finally, I also opted to restructure your code into one Sub rather than two Functions. You weren't returning anything with your AddToArray function which pretty much means by definition it should actually be a Sub
As I stated in a comment to the question, there are a couple of problems in your code before adding anything to the array that will prevent this from working, but assuming that this was caused by simplifying the code to ask the question, the following should work.
The specific question that you are asking, is how to populate the array while increasing its size when needed.
To do this, simply do this:
Instead of:
ReDim Preserve a(size)
For Each rw In sh.Rows
If Match(sh.Cells(rw.Row, 1), s, column) = True Then
Reorder this so that it is:
For Each rw In sh.Rows
If Match(sh.Cells(rw.Row, 1), s, column) = True Then
ReDim Preserve a(size) 'increase size of array
a(size) = sh.Cells(rw.Row,1) 'put value in array
size = size + 1 'create value for size of next array
End If
Next rw
....
This probably isn't the best way to accomplish this task, but this is what you were asking to do. First, increasing the array size EVERY time is going to waste a lot of time. It would be better to increase the array size every 10 or 100 matches instead of every time. I will leave this exercise to you. Then you could resize it at the end to the exact size you want.

Can I Use a Variable to ReDim an Array?

I am not entirely sure why I am getting the error message of
Expecting a dynamic array var
with this code:
Option Explicit
Sub ArrayTest()
Dim i As Integer, BankList(0) As Variant, x As Integer
For i = 0 To UBound(ScreenArray)
If ScreenArray(i) Like "TR=SUB*" Then
Debug.Print ScreenArray(i)
ReDim Preserve BankList(x) '<<< ERROR LINE
BankList(x) = ScreenArray(i)
x = x + 1 'Raise the value for the next occurrence, if needed.
End If
Next
End Sub
Basically I am attempting to move specific strings from one array to a new array, if certain criteria are met. It's difficult to determine how many strings will be in the new array until running this For...Next statement.
If you can't tell from the code, the original array is ScreenArray and the new array is BankList.
To create a dynamic array, do not specify the size in the original declaration.
So use BankList() As Variant instead of BankList(0) As Variant.

Naming an array using a variable

Is it possible to name an array variable using a different variable? For example, if I define variable "i" as an integer with a value equal to the number of columns I've used it a sheet:
Sub varNameTest
Dim i, j, As Integer
i = ActiveSheet.UsedRange.Columns.Count
...
Is it possible to then establish "i" number of arrays named something like myArray1 through i? Possibly something like:
For j = 1 to i
Dim (myArray & j())
Next i
Though this example immediately above is incorrect syntax, I'm just trying illustrate what I'm trying to do.
edit: so to be more clear, using the above example, say I have 4 sheets in a workbook. The variable i would then be 4, and I would have some code that generates myArray1(), myArray2(), myArray3() and myArray4().
You can create an array of arrays (though your question is a little unclear..)
Sub MyArrays()
Dim arrays()
Dim arr
Dim i, j
i = 5 'e.g.
ReDim arrays(1 To i)
For j = 1 To i
arr = Array()
ReDim arr(1 To j)
arrays(j) = arr
Next j
'reference an array by its position in "arrays"
Debug.Print UBound(arrays(3))
End Sub
Yes.
Dim i(5) As Integer
In VBA you can then access elements from i(0) to i(5).
Based on your edited question, the answer is no. You must explicitly define each variable in your code.
The other option would be to write code that writes your code - a form of code generation. Effectively that lets you write very long and complex code by repeating code "templates". But I don't think this would help in your case.

vba, Why an un-dimensioned array works with Split()

I can use an un-dimensioned String array with the Split() function to read fields from a String, but apparently, a String array has to be dimensioned to use it in a loop.
Why is that, and are there other situations where an array does not need to be dimensioned?
Dim field() As String
field = Split(data_line, "~")
Dim pref_line(10) As String
Input #1, pref_line(i)
but apparently, a String array has to be dimensioned to use it in a loop.
When use an un-dimensioned String array with the Split() function, the array is automatically dimensioned and values assigned to it. Also you can use that in a loop using For i = LBound(field) to UBound(field)
Option Explicit
Sub Sample()
Dim field() As String
Dim data_line As String
data_line = "aaa~bbb"
field = Split(data_line, "~")
Debug.Print field(0)
End Sub
Are there other situations where an array does not need to be dimensioned?
Yes. When you do not know how many items needs to be added to an array then you declare and un dimensioned array and Redim Preserve it to add values. For example
Option Explicit
Sub Sample()
Dim field() As Long
Dim n As Long, i As Long
ReDim Preserve field(n)
For i = 1 To 100
field(n) = i
n = n + 1
ReDim Preserve field(n)
Next i
End Sub
Split() returns its own array regardless of what you defined before. You are effectively overwriting the value of your variable.
Dim field() As String declares an array, but does not allocate it.
Dim pref_line(10) As String both declares and allocates it.
field = Split(data_line, "~") both allocates an array and populates it.
Others have already answered your question, and correctly about what you asked for. So I won't comment on that.
On a side note, you should avoid Redimming arrays as much as possible. Do that only when absolutely necessary. Remember that it is just one line of code for us, but a whole lot of work for the runtime engine. First find a new contiguous memory location for the new array; then copy the array items from the old to new one; then discard the old array. So you see one Redim Preserve statement produces how much work for the compiler.
For this reason, redimming inside a loop is "usually" a bad idea, since you know in advance how many times the loop will run and how many elements you will have in the end. So in such cases, redim your array before the start of loop, rather than doing it inside the loop. The end result would be a better performance :)
Taking the code in #SiddharthRout 's reply as an example, notice that the Loop will produce 100 items since you are looping from 1 to 100. So instead of ReDim Preserve field(n) inside the loop, move that outside it before the start of loop. ReDim Preserve field(100) as Long, or simply ReDim field(100) as Long.

Array in excel vba

I want to have an array list in vba, hence I have a variant declared in excel vba like:
Dim Students(10) as variant
Now I want to store numbers in Students list. the numbers are not continuous. Sometime like:
Students(2,7,14,54,33,45,55,59,62,66,69)
How can I do this in vba? also how can I access the list items?
Students must be declared as a dynamic array. That is, an array whose bounds can be changed. Dim Students(10) gives an array whose bounds cannot be changed and cannot be loaded from an array.
Dim Students() As Variant
To load Students:
Students = Array(2,7,14,54,33,45,55,59,62,66,69)
To access the elements:
Dim Inx As Long
For Inx = LBound(Students) to UBound(Students)
Debug.Print Students(Inx)
Next
LBound (Lower bound) and UBound mean that the for loop adjusts to the actual number of elements in Students.
This is too complex for you right now, and you'll probably never run into a situation where you'll need this, but:
I use the following method for forming more memory-efficient arrays (because Variant uses the most memory of any variable type) while still having the convenience of declaring the array contents in one line. To follow your example:
Dim Students() As Long
Dim Array2() As String
Array2() = Split("2,7,14,54,33,45,55,59,62,66,69", ",")
ReDim Array1(0) As Long
For Loop1 = LBound(Array2()) To UBound(Array2())
ReDim Preserve Array1(0 To (UBound(Array1) + 1)) As String
Array1(Loop1) = Array2(Loop1)
Next Loop1
ReDim Preserve Array1(0 To (UBound(Array1) - 1)) As Long
Erase Array2
An example of accessing it would be something like:
For Loop1 = LBound(Students) to UBound(Students)
Msgbox Students(Loop1)
Next Loop1
I learned this from here: http://www.vbforums.com/showthread.php?669265-RESOLVED-VBA-Excel-Assigning-values-to-array-in-a-single-line&p=4116778&viewfull=1#post4116778
You can add values to an Array like this...
For i = 1 to 10
Students(i) = i
Next i
Or like this
Students = Array(2,7,14,54,33,45,55,59,62,66,69)
Then you can access the values in the same manor. Note if you use the second option you'll need to declare it as follows:
Dim Students() As Variant
Well,
That depends on how you would supply the values for the array, would you get the values from Worksheet.Range or from TextBox or ListBox , But basically the code would be something like that :
Dim students(10) as Integer
Dim Carrier as Integer
For i = LBound(students) To UBound(Students)
'some code to get the values you want to from whatever is your source
'then assign the value to Carrier
students(i)=Carrier
Next i
It is not good practice to dim an array as Variant when you certainly know that you are going to use integers only, as it will eat alot of memory that is not needed in the first place.
You also should be aware of the bounds of the numbers that are going to be assigned, if it exceeds the Integer limit then you should use Double or Float.
This is my first participation in the site,Cheers.

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