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Tip of the Day
Language: Visual Basic
Expertise: Beginner
Mar 26, 1999

Is the Array Dimensioned?

Use this function to determine whether a dynamic array has been dimensioned. I use dynamic arrays to store small, foreign key tables locally for fast lookups. Not wanting to load all the arrays initially, I load them only when needed and only once.

I wanted to exploit the fact that the array hasn't yet been dimensioned as the indicator to load, instead of a Boolean variable, but I ran into complications with the standard tests in VB. My function returns True if the dynamic array passed to it has yet to be ReDim'd:

 
Public Function IsArrayEmpty(aArray As Variant) As Boolean
	On Error Resume Next
	IsArrayEmpty = UBound(aArray)
	IsArrayEmpty = Err ' Error 9 (Subscript out of range)
End Function
Use this test code:
 
Option Explicit 

Private Sub cmdTest_Click()
	Dim aDynamic() As Integer
	MsgBox IsArrayEmpty(aDynamic)
	ReDim aDynamic(8)
	MsgBox IsArrayEmpty(aDynamic)
End Sub 
Richard Hundhausen
 
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