vba range to array
'In Excel VBA, the quickest way to pull data from a worksheet into a VBA array
'is to do it all at once:
Dim v As Variant
v = Range("a1:b20").Value
'Please note that, here, 'v' is a scalar variable of type Variant. Scalar means
'that 'v' is NOT an array. But interestingly in this case, 'v' can be
'treated exactly like an array. To understand why, please keep reading...
'Variant variables can be assigned any type of value, for example,
'all of the following are valid:
v = 123
v = 12.19971
v = "abcdefg"
Set v = New Collection
'IN ADDITION, a Variant can also be assigned an entire array, dynamic or static:
Dim v As Variant, arr() As Long
ReDim arr(1 to 4)
arr(1) = 11
arr(2) = 12
arr(3) = 13
arr(4) = 14
v = vArrA
'Now that the array of Longs 'arr' has been assigned to the Variant 'v', we can
'access the elements directly from 'v':
MsgBox v(4) '<--displays: 14
'A very efficient way to read data from a worksheet range is to directly assign
'the data to a Variant holding an array of Variants:
v = Sheet1.Range("a1:b20").Value
'The 'Value' property of the Range object creates a 2D array of Variant
'elements the same size as the specified range, in this case,
'20 rows of 2 columns, with a lower bound of 1 for both dimensions.
'Here, we assign that array directly to the scalar Variant 'v', all in one go.
'The scalar Variant 'v' can now be treated as an array, even though it is
'actually a scalar variable that points to an array THAT WAS NEVER NAMED:
MsgBox v(2, 20) '<--displays: the value that was in Sheet1, cell B20
'As long as the worksheet range consists of more than one cell, this method
'always results in an array and that array is always 2D. It is never 1D. If
'the range consists of only ONE cell, then this method does NOT create an
'array; instead, it assigns that one cell's scalar value to the Variant 'v'.
'This method is very convienent and its use is common. The code can even
'be shortened:
v = [Sheet1!a1:b20]
'The square brackets are a shorthand notation for VBA's Evaluate() function.
'This shorthand produces exactly the same results as the previous example,
'because the Evaluate() function returns a Range object in this instance and
'the default property of the Range object is the 'Value' property.
'In the above examples, the Range object is returning its
'default... the Range.Value property. But keep in mind that the
'Range.Value2 property is roughly 20% quicker. So it slightly more
'performant to code these two examples like so:
v = [Sheet1!a1:b20].Value2
v = Sheet1.Range("a1:b20").Value2
'Note: VBA utilizes the OLE SAFEARRAY data structure for its
' array implementation:
' https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-oaut/2e87a537-9305-41c6-a88b-b79809b3703a
' https://ecs.syr.edu/faculty/fawcett/Handouts/cse775/presentations/BruceMcKinneyPapers/safeArrays.htm
' http://www.roblocher.com/whitepapers/oletypes.html
'
'
'
v = [a1:b20]
'If v is dimensioned as a variant then he above creates a 2d array,
'20 rows high by 2 columns wide and those 40 array elements contain
'the values from the specified range.
'The square brackets are shorthand notation. Another way to code the
'same thing is:
v = Range("a1:b20")
'In both of the above examples, the Range object is returning its
'default... the Range.Value property. But keep in mind that the
'Range.Value2 property is about 20% quicker. So it could be more
'performant to code these two examples like so:
v = [a1:b20].Value2
v = Range("a1:b20").Value2
