declaring arrays in excel vba code example
Example 1: vba string array
'In VBA a dynamic string array is declared in the following ways:
Dim strArr1() As String
Dim strArr2$()
'Neither declaration style is prefered. They are exactly equivalent.
'Both ways above produce a dynamic array, which means that the exact size of
'the array (how many elements) is specified later in code:
Redim strArr1(1 to 10)
'To instead declare a static string array (an array with a fixed size),
'specify the size within the Dim statement:
Dim strArr1(1 to 10) As String
Dim strArr2$(0 to 4)
'ReDim() cannot later be used on static arrays. Their size is fixed.
'Once a string array is declared, the array elements are assign one at a time:
strArray1(1) = "abc"
'However, the Split() function can be used to split a string and assign to and
'to also size a dynamic string array in one go:
Dim strArr3$()
strArray3 = Split("a,b,c", ",")
'strArray3 will now contain three elements, "a", "b", and "c".
'Note: String arrays can only conatin text values. When numbers are assigned
' to string array elements, the number is first coerced to a string value.
' Boolean and Date values are likewise coerced to text values.
' Objects CANNOT be assinged to string array elements.
'
' For the above reasons (and especially with Excel data) it may be better
' to declare and use Variant arrays instead of String arrays. Variants
' can be assigned any data type. The trade-off is that manipulating
' Variants is slightly slower than base data types.
'
' Variants are the default data type in VBA so the following declares
' an array of Variants:
Dim vArr1()
' But the data type may also be specified explicitly:
Dim vArr1() As Variant
' The Variant data type does not have a specific Type Declaration Character.
' For example, the String data type has the '$' type declaration character
' which was demonstrated at the top of this page. But since the Variant is
' VBA's default, no type declaration character is needed. Not specifying
' a type results in a variable's type being a Variant, by default.
'Note: it is important to realize that since a Variant can hold any other type
' of data, it can also hold an array. It is EXTREMELY common in VBA to
' declare a single Variant variable that will later be assinged an array:
Dim v
' The above variable is a single Variant. It is not an array. Variants
' can be assinged numbers, dates, Booleans, error values, objects,
' essentially anything. And in addition, variants can also
' be assigned arrays of any type:
v = Array(1, 2, 3, "a", "b", "c", True, False, #1/1/2021#)
' The above line creates an array of 9 Variant values and assigns the
' entire array to the Variant existing variable, 'v'.
'
' Perhaps the most common way to assign an array of Variants to
' an existing Variant variable is to pull data from a worksheet range:
v = Sheet1.Range("A1:A10").Value
' The above statement assigns a 2-dimension array to v, ten rows deep
' and one column wide. The values and data types of the
' ten elements will correspond to the values and types
' in the Sheet1 range, A1:A10. It is important to realize that
' the VBA array created here is a copy of the data in the worksheet
' range. Changing one does not affect the other. But it is possible
' to write the VBA array back to Excel to the original range, or
' to any range in any worksheet in any open workbook.
'
'
'Example 2: excerl vba array to range
arrayData = Array("A", "B", "C", "D", "E")
[a1].Resize(UBound(arrayData)) = Application.Transpose(arrayData)Example 3: excel vba initialize entire array
'VBA function to create a 2D array with every element set
'to the same initial value:
Function Init2D(rows, cols, Optional val)
Dim i&, j&
ReDim v(1 To rows, 1 To cols)
If Not IsMissing(val) Then
For i = 1 To rows
For j = 1 To cols
v(i, j) = val
Next
Next
End If
Init2D = v
End Function
'This version uses no loops:
Function Init2D(rows, cols, Optional val = "")
Const NUMER = "index(offset(a1,,,ROWS,COLS)*0+VAL,,)"
Const ALPHA = "index(rept("""",len(offset(a1,,,ROWS,COLS))<0)&""VAL"",,)"
DoEvents
Init2D = Evaluate(Replace(Replace(Replace(IIf(IsNumeric(val), NUMER, ALPHA), "VAL", val), "ROWS", rows), "COLS", cols))
End Function
'--------------------------------------------------------------------
'10 rows, 1 column, all elements = 0:
a = Init2D(10, 1, 0)
'20 rows, 5 columns, all elements = "abc":
a = Init2D(20, 5, "abc")
'--------------------------------------------------------------------
'1D array version:
Function Init1D(elems, Optional val, Optional base = 1)
Dim i&, max&
max = base + elems - 1
ReDim v(base To max)
If Not IsMissing(val) Then
For i = base To max
v(i) = val
Next
End If
Init1D = v
End FunctionExample 4: vba array
'VBA arrays can be fixed-size (static) or resizable (dynamic).
'This is determined when the array is declared:
Dim vArrA() 'dynamic: size is determined later.
Dim vArrB(1 to 5) 'static: size is determined now and cannot be changed.
'Array size refers to the number of elements in the array. For example, vArrB()
'above has five elements. The "1 to 5" is referred to as the array's range of
'indices. The range size must be positive, meaning the number of elements must
'be positive. This means that the 2nd integer in the range must be greater
'or equal to the first integer.
'VBA is unusual among programming languages with regards to the lowerbound or
'the base, of arrays. Most languages require arrays to have a base (or lowerbound)
'of zero. VBA arrays can have lowerbounds of ANY Long Integer value
'(-2147483648 through +2147483647). So, all of the following are valid:
Dim vArrC(0 to 9)
Dim vArrD(1 to 10)
Dim vArrE(11 to 20)
Dim vArrF(-8877 to -8868)
Dim vArrG(-5 to 4)
'vArrC through vArrG are perfectly legal and each has precisely 10 elements. Note
'that the size AND the bounds are fixed for static arrays. Both of these
'attributes can be changed for dynamic arrays whenever the need arises:
ReDim vArrA(1 to 1000)
'And at a later point:
ReDim vArrA(0 to 4)
'A third attribute of VBA arrays is the number of dimensions. Every example on
'this page thus far represents a 1D array. Another term for a one-dimensional
'array is vector. A vector does not really have rows or columns, just
'elements.
'However, when writing a 1D array to a worksheet, Excel treats the array as if
'it were a 2D array consisting of 1 row and n colums (where n is equal to the
'number of elements). This fact causes confusion for many.
'Consider:
ReDim vArrA(1 to 5)
vArrA(1) = "m"
vArrA(2) = "n"
vArrA(3) = "o"
vArrA(4) = "p"
vArrA(5) = "q"
Sheet1.Range("A1:E5") = vArrA
'Sheet1 now has the following values:
' A B C D E
'1 m n o p q
'2 m n o p q
'3 m n o p q
'4 m n o p q
'5 m n o p q
'This is why Transpose() is required to write the 1D array vertically:
Sheet1.Range("A1:E5") = WorksheetFunction.Transpose(vArrA)
'Sheet1 now has the following values:
' A B C D E
'1 m m m m m
'2 n n n n n
'3 o o o o o
'4 p p p p p
'5 q q q q q
'Notice that the one array with five elements can be written to multiple rows
'or with Transpose() to multiple columns. Of course, the array can be
'written to one row:
Sheet1.Range("A1:E1") = vArrA
'Or to one column:
Sheet1.Range("A1:A5") = WorksheetFunction.Transpose(vArrA)
'Since Excel treats 1D arrays (vectors) oddly when writing to a worksheet, it
'can be easier to work with 2D arrays. In Excel VBA, 2D arrays are row major.
'This means that rows are represented by the first dimension and columns are
'represented by the second.
ReDim vArrA(1 to 5, 1 to 10)
' ^rows ^cols
'vArrA is now sized as a 2D array with 5 rows of 10 columns. It can be written
'to a worksheet with 5 rows of 10 columns without using Transpose().
'Size, lower and upper bounds, and number of dimensions
'are all fixed for static arrays and they are all specified when the array is
'declared:
Dim vArrH(0 to 9, 1 to 10)
'vArrH is a static 2D array of 100 elements, 10 rows of 10 columns, with
'0 as the lowerbound for the first dimension (the rows) and 1 as the lowerbound
'of the second dimension (the columns). None of these attributes can later
'be changed for vArrH, since it is a static (or fixed) array. In contrast,
'all three of these attributes can be changed for a dynamic array... at any time.
'The max number of dimensions supported for an array is 60, though
'it is unusual to use arrays with more than 3 dimensions. Conceptually, a
'1D array is a vector, a 2D array can be thought of as a worksheet with rows
'and columns, a 3D array can be thought of as a workbook with multiple
'worksheets (or a cube), and a 4D array can be thought of a folder of workbooks
'(or perhaps a hypercube). But keep in mind that each dimension can be declared
'with a different number of elements. For example, a 4D dynamic array:
ReDim vArrA(0 to 4, 1 to 10, 3 to 7, 1 to 2)
' ^rows ^cols ^sheets ^books
'A fourth attribute of arrays is the data type. VBA's default data type
'is the Variant. If no data type is specified then by default the data type is actually Variant. So all the
'examples so far are Variant arrays, that is an array where every single element
'is of data type Variant.
'Here are some other data type array examples. They can be written verbosely
'or in some cases with a type declaration character:
Dim a() As Double 'or... Single, Short, Long, Currency, String, Byte, Date
'or... Boolean, UserDefinedType, ClassName, Object
Dim a#() 'or... a!(), a%(), a&(), a@(), a$()
'Note: 64bit VBA also includes the LongLong data type:
Dim a() As LongLong 'or... a^()