check if array is empty (vba excel) - excel

Question

These if ... then statements are getting the wrong results in my opinion. The first is returning the value 'false' when it should be 'true'. The fourth returns the right value. The second and third return an error.
Sub empty_array()
Dim arr1() As Variant
If IsEmpty(arr1) Then
MsgBox "hey"
End If
If IsError(UBound(arr1)) Then
MsgBox "hey"
End If
If IsError(Application.match("*", (arr1), 0)) Then
MsgBox "hey"
End If
ReDim arr1(1)
arr1(1) = "hey"
If IsEmpty(arr1) Then
MsgBox "hey"
End If
End Sub

Answer 1

Arr1 becomes an array of 'Variant' by the first statement of your code:
Dim arr1() As Variant
Array of size zero is not empty, as like an empty box exists in real world.
If you define a variable of 'Variant', that will be empty when it is created.
Following code will display "Empty".
Dim a as Variant
If IsEmpty(a) then
MsgBox("Empty")
Else
MsgBox("Not Empty")
End If

Answer 2

Adding into this: it depends on what your array is defined as. Consider:
dim a() as integer
dim b() as string
dim c() as variant
'these doesn't work
if isempty(a) then msgbox "integer arrays can be empty"
if isempty(b) then msgbox "string arrays can be empty"
'this is because isempty can only be tested on classes which have an .empty property
'this do work
if isempty(c) then msgbox "variants can be empty"
So, what can we do? In VBA, we can see if we can trigger an error and somehow handle it, for example
dim a() as integer
dim bEmpty as boolean
bempty=false
on error resume next
bempty=not isnumeric(ubound(a))
on error goto 0
But this is really clumsy... A nicer solution is to declare a boolean variable (a public or module level is best). When the array is first initialised, then set this variable.
Because it's a variable declared at the same time, if it loses it's value, then you know that you need to reinitialise your array.
However, if it is initialised, then all you're doing is checking the value of a boolean, which is low cost. It depends on whether being low cost matters, and if you're going to be needing to check it often.
option explicit
'declared at module level
dim a() as integer
dim aInitialised as boolean
sub DoSomethingWithA()
if not aInitialised then InitialiseA
'you can now proceed confident that a() is intialised
end sub
sub InitialiseA()
'insert code to do whatever is required to initialise A
'e.g.
redim a(10)
a(1)=123
'...
aInitialised=true
end sub
The last thing you can do is create a function; which in this case will need to be dependent on the clumsy on error method.
function isInitialised(byref a() as variant) as boolean
isInitialised=false
on error resume next
isinitialised=isnumeric(ubound(a))
end function

Answer 3

#jeminar has the best solution above.
I cleaned it up a bit though.
I recommend adding this to a FunctionsArray module
isInitialised=false is not needed because Booleans are false when created
On Error GoTo 0 wrap and indent code inside error blocks similar to with blocks for visibility. these methods should be avoided as much as possible but ... VBA ...
Function isInitialised(ByRef a() As Variant) As Boolean
On Error Resume Next
isInitialised = IsNumeric(UBound(a))
On Error GoTo 0
End Function

Answer 4

I would do this as
if isnumeric(ubound(a)) = False then msgbox "a is empty!"

Answer 5

I may be a bit late, but following simple stuff works with string arrays:
Dim files() As String
files = "..." 'assign array
If Not Not files Then
For i = LBound(files) To UBound(files)
'do stuff, array is not empty
Next
End If
That's all the code for this.

Answer 6

Above methods didn´t work for me. This did:
Dim arrayIsNothing As Boolean
On Error Resume Next
arrayIsNothing = IsNumeric(UBound(YOUR_ARRAY)) And False
If Err.Number <> 0 Then arrayIsNothing = True
Err.Clear
On Error GoTo 0
'Now you can test:
if arrayIsNothing then ...

Answer 7

this worked for me:
Private Function arrIsEmpty(arr as variant)
On Error Resume Next
arrIsEmpty = False
arrIsEmpty = IsNumeric(UBound(arr))
End Function

Answer 8

The problem with VBA is that there are both dynamic and static arrays...
Dynamic Array Example
Dim myDynamicArray() as Variant
Static Array Example
Dim myStaticArray(10) as Variant
Dim myOtherStaticArray(0 To 10) as Variant
Using error handling to check if the array is empty works for a Dynamic Array, but a static array is by definition not empty, there are entries in the array, even if all those entries are empty.
So for clarity's sake, I named my function "IsZeroLengthArray".
Public Function IsZeroLengthArray(ByRef subject() As Variant) As Boolean
'Tell VBA to proceed if there is an error to the next line.
On Error Resume Next
Dim UpperBound As Integer
Dim ErrorNumber As Long
Dim ErrorDescription As String
Dim ErrorSource As String
'If the array is empty this will throw an error because a zero-length
'array has no UpperBound (or LowerBound).
'This only works for dynamic arrays. If this was a static array there
'would be both an upper and lower bound.
UpperBound = UBound(subject)
'Store the Error Number and then clear the Error object
'because we want VBA to treat unintended errors normally
ErrorNumber = Err.Number
ErrorDescription = Err.Description
ErrorSource = Err.Source
Err.Clear
On Error GoTo 0
'Check the Error Object to see if we have a "subscript out of range" error.
'If we do (the number is 9) then we can assume that the array is zero-length.
If ErrorNumber = 9 Then
IsZeroLengthArray = True
'If the Error number is something else then 9 we want to raise
'that error again...
ElseIf ErrorNumber <> 0 Then
Err.Raise ErrorNumber, ErrorSource, ErrorDescription
'If the Error number is 0 then we have no error and can assume that the
'array is not of zero-length
ElseIf ErrorNumber = 0 Then
IsZeroLengthArray = False
End If
End Function
I hope that this helps others as it helped me.

Answer 9

I'm using this
If UBound(a) >= 0 Then
' not empty
Else
' empty... UBound(a) = -1
End If
IsEmpty(a) did not work for me... I hate VBA
Dim arr() As Variant
Debug.Print IsEmpty(arr) ' False
Debug.Print UBound(arr) ' raises error
arr = Array()
Debug.Print IsEmpty(arr) ' False
Debug.Print UBound(arr) ' -1
ReDim Preserve arr(UBound(arr) + 1)
arr(UBound(arr)) = "test"
Debug.Print IsEmpty(arr) ' False
Debug.Print UBound(arr) ' 0

Answer 10

The below function works for both static and dynamic arrays.
Function array_Empty(testArr As Variant) As Boolean
Dim i As Long, k As Long, flag As Long
On Error Resume Next
i = UBound(testArr)
If Err.Number = 0 Then
flag = 0
For k = LBound(testArr) To UBound(testArr)
If IsEmpty(testArr(k)) = False Then
flag = 1
array_Empty = False
Exit For
End If
Next k
If flag = 0 Then array_Empty = True
Else
array_Empty = True
End If
End Function

Answer 11

Tente isso:
Function inic(mtz As Variant) As Boolean
On Error Resume Next
Dim x As Boolean
x = UBound(mtz): inic = x
End Function
...
if inic(mymtz) then
debug.print "iniciada"
else
debug.print "não iniciada"
end if