Non-Repeating Random Numbers

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

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,

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.

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

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

End Class