is it possible to start an array with negative value vb. net

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Here is my visual basic code

VB

Sub info()
If False=0 Then
ReDim W(-2 to N+2)
End If

this Coding working in vb 6.0 
But the same coding transferred to vb.net it shows an error Array lower bound to be  0

Can any one please guide me how to fix this issue

Posted 27-Sep-15 0:33am

Bensingh

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Wendelius · Accepted Answer · 2015-09-27T00:43:00

An array cannot have a negative index. So as far as I can see you have three options:
- modify the code to use 0 based arrays
- use 0 based indexing but when using the index subtract/add 2, depending on the situation.
- use a Dictionary(Of TKey, TValue) Class[^]

Some examples

VB

Dim N1 As Integer = 100
Dim W1(0) As Integer
ReDim W1(0 To N1 + 4)

For counter As Integer = 0 To 104
   W1(counter) = counter
Next

Dim N2 As Integer = 100
Dim W2(0) As Integer
ReDim W2(0 To N2 + 4)

For counter As Integer = -2 To 102
   W2(counter + 2) = counter
Next

Dim W3 As System.Collections.Generic.Dictionary(Of Integer, Integer)
W3 = New Dictionary(Of Integer, Integer)
For counter As Integer = -2 To 102
   W3.Add(counter, counter)
Next

Maciej Los · Accepted Answer · 2015-09-27T01:21:00

Vb6 is not the same as VB.Net. There's a lot of differencies between them. I'd suggest to read this: Upgrading Visual Basic 6.0 Applications to Visual Basic .NET and Visual Basic 2005[^] and this: omparison of Visual Basic and Visual Basic .NET[^] to find out.

You did not provide information about what you want to achieve, but Redim instruction[^] is usually used to reallocate storage space for an array variable. You can increase/decrease the size of array, but you need to remember that low index of array cannot be negative, because arrays are zero based, unless you use Option Base 1 statement[^]. Note that ReDim W(N-2 to N+2) statement creates new array and destoroys original one. If you want to save original array, use Preserve keyword.

As Mika Wendelius[^] mentioned, you can use Dictionary class, but this is not the only way. Depending on what you want to achieve, you can use custom class to manage data.

For further information, please see:
Visual Basic[^]
Creating Classes in Visual Basic .NET[^]
Using Classes and Structures in Visual Basic .NET[^]
Walkthrough: Defining Classes (Visual Basic)[^]

is it possible to start an array with negative value vb. net

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