Arrays of Structs in Structs 1

[NBartomeli]

I am trying to create arrays of structs nested in other structs in my class, as follows:

<Serializable()> _
Public Structure clsEquityTrackerMetric
	Public Name As String
	Public Measure As String
	Public MeasureID As String
	Public MeasureType As String
	Public ThresholdHigh As Integer
	Public ThresholdLow As Integer
End Structure

<Serializable()> _
Public Structure clsEquityTrackerGroup
	Public Name As String
	Public ID As Integer
	Public SubGroup() As clsEquityTrackerSubGroup
End Structure

<Serializable()> _
Public Structure clsEquityTrackerSubGroup
	Public Name As String
	Public ID As Integer
	Public Metric() As clsEquityTrackerMetric
End Structure

My problem is when I do a statement like: "Redim Preserve subgroup.metric(+1)", on the first pass it makes an array of 2, not one. If I try to assign a value to the array in position 0 without a redim, I get a "not set to an instance of object" error.

Is there any way around this? Thanks

 

[JohnYingling]

Arrays in VB.Net (as in VB6) are allocated by UpperBound not by Count. An empty array is (-1), a 1 element array is (0).

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[Borvik]

One thing to remember though - when getting the UpperBound - if you try to do this on an empty array you will still get your "not set to an instance of object" error.

 

[JohnYingling]

Borvik,

Change that "empty array" to "unallocated" array.
Dim UnallocatedArray() as Integer
Dim EmptyArray(-1) as Integer

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[Borvik]

Right JohnYingling 8P

When declaring a dynamic array I tend to think that it is empty right off the bat, and not unallocated.

Another thing that might be helpful though is to use a numeric variable to keep track of your array counts. Default it to -1 and increment when you before you redim the array, or default it to 0 and increment after the redim. If you were going to do that I would suggest putting the numeric var in the structs that declare the dynamic array.

 

[JohnYingling]

An Arraylist might be better.

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