Hello I 5 unique numbers betwen 0 and 10, I'm doing as following :
Dim RandomClass As New Random()
Dim RandomNumber As Integer
For counter As Integer = 0 To 5
RandomNumber = RandomClass.Next(0, 10)
MsgBox(RandomNumber )
Next
Sometimes it works, I get those numbers : "1,7,4,9,3" but sometimes I get a duplicate numbers like : "5,2,3,2,7"
How can I be sure to have unique numbers each time?
Thank you.
Use HashSet(Of Integer) to remember numbers that have already been printed out:
Dim RandomClass As New Random()
Dim RememberSet As New HashSet(Of Integer)
Dim RandomNumber As Integer
While RememberSet.Count < 5
RandomNumber = RandomClass.Next(0, 10)
If RememberSet.Add(RandomNumber) Then
MsgBox(RandomNumber)
End If
End While
Just for fun, a different approach, make a list of integers from 0 to 10, use the random generator to get an index inside this list, print that number and remove from the list. Keep the generation of the random numbers inside the limits
Dim numbers = Enumerable.Range(0, 11).ToList()
Dim RandomClass As New Random()
Dim RandomIndex As Integer
For counter As Integer = 1 To 5
RandomIndex = RandomClass.Next(0, numbers.Count)
MsgBox(numbers(RandomIndex))
numbers.RemoveAt(RandomIndex)
Next
var numbers = Enumerable.Range(0, 11).OrderBy(n => RandomClass.Next()).Take(5) although it's probably not as efficient.I would suggest adding a seed so that random numbers are not repeated.
Dim RandomClass As New Random(DateTime.Now.Ticks)
Dim RememberSet As New HashSet(Of Integer)
Dim RandomNumber As Integer
While RememberSet.Count < 5
RandomNumber = RandomClass.Next(0, 10)
If RememberSet.Add(RandomNumber) Then
MsgBox(RandomNumber)
End If
End While
Dim RandomClass As New Random(DateTime.Now.Ticks) gives a System.OverflowExceptiontry following:
Sub Main()
Dim a As String() = New String(2) {}
Dim b As String
Dim c As Integer = 0
Dim d As String = " "
Do
Console.Clear()
Console.Write("Enter your name:")
a(c) = Console.ReadLine()
c += 1
Loop Until c = 3
For Each d In a
Console.Write(" " & d)
Next
Console.ReadLine()
