borderAndreaVB free resources for Visual Basic developersborder
borderAndreaVB Visual Basic and VB.NET source code resources - Copyright © 1999-2014 Andrea Tincaniborder

AndreaVB | Forum | News | Downloads | Register | Help | Member List | Statistics | Search | PM | Profile

Print This Topic
Previous Topic (Simple Fixed Array Part 1)Next Topic (Easily Backup and Restore an SQL Server/MSDE database) New Topic New Poll Post Reply
AndreaVB Forum : Articles and tutorials : Non-Repeating Random Numbers, or anything you want.
Poster Message
Graham
Level: Protégé

Registered: 08-01-2007
Posts: 5

icon Non-Repeating Random Numbers, or anything you want.

Here is a simple tutorial to help pick six non-repeating numbers or any non-repeating elements you want to use. i.e. the Alphabet.
As always we start with the Dim statements


Dim intNumber As Integer
    Dim arrNumber(0 To 5) As Integer
    Dim i, x, y As Integer


There are only two controls needed on the form one is a Button and the other is a Label.
In the Buttons Event Procedure.is where all the code is placed to pick the random numbers and display the results in the Label.
First make sure that the Label is empty.

Label1.Text = ""


Now we need to set up a For / Next Loop to hold six numbers,

For x = 0 To 5
Next x


So, our For / Next Loop will go around six times, but without some more code it will not be very interesting.

What follows next is the code that will do the magic.
You will notice that inside our For / Next x Loop we have a nested For / Next y Loop.
This is the Loop that checks if the Random number has already been picked.
How? Well, first the random number is checked to see if it exists in our arrNumber(y), remember the tutorials on Arrays? So it looks at the first place in the array which first time the loop is entered is (0) in fact this is what the array looks like to start with.
arrNumber(0) = 0
arrNumber(1) = 0
etc
arrNumber(5) = 0
After the y Loop has finished and no numbers in the arrNumber have been found it moves on to the last bit of code inside the x For / Next Loop so that we get, assuming our first Random Number was 19 the following
arrNumber(0) = 19 once this is done off it goes again
First y Loops to see if the second Random Number has been already been picked.
Array y now looks like this
arrNumber(0) = 19
arrNumber(1) = 0
etc
arrNumber(5) = 0

If the second Random Number is 38 then as it Loops through the y Array it will not find 38, so it moves on and places 38 in the x Array (Not Medical!)
Off it goes again this time let’s say the Random Number is 19 again, as the y Loop is performed it finds 19 in arrNumber (0) position so now it uses GoTo and jumps up to Start: where it picks another Random Number to try, it keeps doing this until all six places in the Array are filled with Non-Repeating Numbers.
See the code below.

     For x = 0 To 5
Start:
            Randomize()
            intNumber = Int((49 * Rnd()) + 1
            For y = 0 To 5                
                If intNumber = arrNumber(y) Then
                    GoTo Start
                End If
            Next y

            
            arrNumber(x) = intNumber
         Next x



The last stage is to place the numbers in to the Label

For i = 0 To 5
            Label1.Text = Label1.Text & (arrNumber(i)) & " , "
        Next


The full code is here for you to Copy (Ctrl+C) and Paste (Ctrl+V)


Public Class Form1
    ' Dimension the variables used in the programme
    Dim intNumber As Integer
    Dim arrNumber(0 To 5) As Integer
    Dim i, x, y As Integer
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        'Make sure the Label is clear
        Label1.Text = ""

        'We want a total of 6 Numbers (UK Lottery)

        For x = 0 To 5
Start:
            Randomize()
            intNumber = Int((49 * Rnd()) + 1) ' Random number 1 to 49
            For y = 0 To 5
                ' Check arrNumber (y)
                'If intnumber has already been selected,
                'Then go and select another one.
                If intNumber = arrNumber(y) Then
                    GoTo Start
                End If
            Next y

            'Place the next non-repeated number in the arrNumber(x).
            arrNumber(x) = intNumber
            
        Next x
        '----------------------------------------------------
        For i = 0 To 5
            Label1.Text = Label1.Text & (arrNumber(i)) & " , "
        Next
        
    End Sub
    
End Class






____________________________
Clever knows the Answers,
Wise knows where to find them.

08-01-2007 at 02:51 PM
View Profile Send Email to User Show All Posts | Quote Reply
AndreaVB Forum : Articles and tutorials : Non-Repeating Random Numbers, or anything you want.
Previous Topic (Simple Fixed Array Part 1)Next Topic (Easily Backup and Restore an SQL Server/MSDE database) New Topic New Poll Post Reply
Surf To:


Not Logged In? Username: Password: Lost your password?
borderAndreaVB free resources for Visual Basic developersborder
borderAndreaVB Visual Basic and VB.NET source code resources - Copyright © 1999-2014 Andrea Tincaniborder