Question

How to use ReDim Preserve to resize an array in VB.NET

Answer 1

Module Module1

    Sub Main()

        Dim arr() As Integer = New Integer() {1, 2, 3, 4}

        For i As Integer = 0 To arr.Length - 1
            Console.Write("{0, 3}", arr(i))
        Next

        ReDim Preserve arr(5)

        Console.WriteLine()
        For i As Integer = 0 To arr.Length - 1
            Console.Write("{0, 3}", arr(i))
        Next

    End Sub

End Module

'run:
' 
'  1  2  3  4
'  1  2  3  4  0  0

 

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Answer 2

Module Module1

    Sub Main()

        Dim arr() As Integer = New Integer() {1, 2, 3, 4}

        For i As Integer = 0 To arr.Length - 1
            Console.Write("{0, 3}", arr(i))
        Next

        ReDim Preserve arr(1)

        Console.WriteLine()
        For i As Integer = 0 To arr.Length - 1
            Console.Write("{0, 3}", arr(i))
        Next

    End Sub

End Module

'run:
' 
'  1  2  3  4
'  1  2

 

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Answer 3

Module Module1

    Sub Main()

        Dim arr() As Integer = New Integer() {1, 2, 3, 4}

        For i As Integer = 0 To arr.Length - 1
            Console.Write("{0, 3}", arr(i))
        Next

        ReDim Preserve arr(5)

        arr(4) = 77
        arr(5) = 88

        Console.WriteLine()
        For i As Integer = 0 To arr.Length - 1
            Console.Write("{0, 3}", arr(i))
        Next

    End Sub

End Module

'run:
' 
'  1  2  3  4
'  1  2  3  4 77 88

 

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