是否有可能以负值vb开始一个数组.网 [英] is it possible to start an array with negative value vb. net

问题描述

这是我的视觉基本代码

Here is my visual basic code

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 

谁能指导我如何解决此问题?

Can any one please guide me how to fix this issue

推荐答案

数组不能具有负索引.据我所知，您有三个选择:
-修改代码以使用基于0的数组
-使用基于0的索引，但根据情况使用索引减法/加法2，
-使用字典(TKey，TValue)( [ ^ ]

一些例子

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

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

Vb6与VB.Net不同.它们之间有很多差异.我建议阅读以下内容:将Visual Basic 6.0应用程序升级到Visual Basic .NET和Visual Basic 2005 [ ^ ]并执行以下操作: 对Visual Basic和Visual Basic .NET的比较 [ Redim指令 [ ^ ]通常用于为数组变量重新分配存储空间.您可以增加/减少数组的大小，但是要记住，数组的低索引不能为负，因为数组是基于零的，除非您使用米卡·温德留斯 [ Visual Basic [在Visual Basic .NET中创建类 [在Visual Basic .NET中使用类和结构 [ ^ ]
演练:定义类(Visual Basic) [

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)[^]

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