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.

If my answer solved your problem then please remember to mark it as accepted by pressing the tick/check mark on its left. -- More info can be found here: [**How does accepting an answer work?**](http://meta.stackexchange.com/questions/5234/how-does-accepting-an-answer-work) — Visual Vincent, Feb 19 '17 at 10:16
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) — zaggler, 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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