Creating a specified number of strings

Question

I want to create a specified number of strings in a VB.NET Console Application. I've tried this code but it throws an exception:

NullReferenceException: Object Reference not set into an instance of an Object.

This is the code:

Module RandStrConsole

Dim r As New Random
Dim s As String
Dim result As System.Text.StringBuilder
Dim sb As System.Text.StringBuilder
Dim MaxChar As Integer


Sub Main()

    Console.Write("Enter String: ") : s = Console.ReadLine
    Console.Write("Maxchar: ") : MaxChar = Console.ReadLine

    For i As Integer = 1 To MaxChar

        Dim idx As Integer = r.Next(0, s.Count - 1)
        result = sb.Append(s.Substring(idx, 1)) 'NullReferenceException: Object Reference not set into an instance of an Object.
        result.ToString()

    Next

    Console.WriteLine(result)
    Console.ReadKey()


End Sub

End Module

The commented section indicates where the exception happened.

Thanks @VisualVincent, I hope you can reach more people to help! — Karuntos, Feb 19 '17 at 10:43
Your issue explained in detail [What is a NullReferenceException, and how do I fix it?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — Trevor, Feb 19 '17 at 13:57

score -1 · Accepted Answer · answered Feb 19 '17 at 09:32

-1

You forgot to initialize the StringBuilders. You must use the New keyword.

Dim result As New System.Text.StringBuilder
Dim sb As New System.Text.StringBuilder

answered Feb 19 '17 at 09:32

Visual Vincent

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Creating a specified number of strings

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