How to create non-repeating random numbers in VB - vb.net

Question

I'm creating a simple game in VB, as the player takes a shot, the is a random chance it will miss, as multiple shots are taken in each point, i new a new random number when the "Sub playShot()" repeats, the number needs to be between 1 and 10.
This is what i currently have, but it just outputs the same number:
Dim rnd As New Random
Dim shot As Integer = rnd.Next(1, 11)
I'm fine if it repeats the number due to chance, but currently it is always the same.

Answer 1

It just so happens that I have a project open right now that contains extension methods for randomising a list of objects:
Imports System.Runtime.CompilerServices
''' <summary>
''' Contains methods that extend the <see cref="IEnumerable(Of T)"/> interface.
''' </summary>
Public Module EnumerableExtensions
''' <summary>
''' A random number generator.
''' </summary>
Private rng As Random
''' <summary>
''' Randomises the items in an enumerable list.
''' </summary>
''' <typeparam name="T">
''' The type of the items in the list.
''' </typeparam>
''' <param name="source">
''' The input list.
''' </param>
''' <returns>
''' The items from the input list in random order.
''' </returns>
<Extension>
Public Function Randomize(Of T)(source As IEnumerable(Of T)) As IEnumerable(Of T)
EnsureRandomInitialized()
Return source.Randomize(rng)
End Function
''' <summary>
''' Randomises the items in an enumerable list.
''' </summary>
''' <typeparam name="T">
''' The type of the items in the list.
''' </typeparam>
''' <param name="source">
''' The input list.
''' </param>
''' <param name="random">
''' A random number generator.
''' </param>
''' <returns>
''' The items from the input list in random order.
''' </returns>
<Extension>
Public Function Randomize(Of T)(source As IEnumerable(Of T), random As Random) As IEnumerable(Of T)
Return source.OrderBy(Function(o) random.NextDouble())
End Function
''' <summary>
''' Initialises the random number generator if it is not already.
''' </summary>
Private Sub EnsureRandomInitialized()
rng = If(rng, New Random)
End Sub
End Module
With that module in your project, you can do things like this:
Dim numbers = Enumerable.Range(1, 10).Randomize()
For Each number In numbers
Console.WriteLine(number)
Next
That module contains two overloads, with the second allowing you to pass in your own Random instance if desired. If you only ever want to use the first overload then the module can be simplified somewhat:
Imports System.Runtime.CompilerServices
''' <summary>
''' Contains methods that extend the <see cref="IEnumerable(Of T)"/> interface.
''' </summary>
Public Module EnumerableExtensions
''' <summary>
''' A random number generator.
''' </summary>
Private rng As Random
''' <summary>
''' Randomises the items in an enumerable list.
''' </summary>
''' <typeparam name="T">
''' The type of the items in the list.
''' </typeparam>
''' <param name="source">
''' The input list.
''' </param>
''' <returns>
''' The items from the input list in random order.
''' </returns>
<Extension>
Public Function Randomize(Of T)(source As IEnumerable(Of T)) As IEnumerable(Of T)
rng = If(rng, New Random)
Return source.OrderBy(Function(o) rng.NextDouble())
End Function
End Module

Answer 2

When you have a range where you don't want the random values to repeat, the normal solution is to generate all the numbers in the range (in this case 1 through 10) in sequence. Then you shuffle the sequence. Now you can iterate through your shuffled data.