Jon,
Thanks for the input! The reason I was thinking arraylist was because
the "list" of items will actually come from the selected items in a ListBox.
The ListBox connects to a database and the user can select from the items in
it to narrow create the list of items to be randomized. I'll give your code a
shot, although I have to convert it to VB. :)
Thanks again,
Steve
"Jon Skeet [C# MVP]" wrote:
[color=blue]
> Fieldmedic <Fieldmedic@discussions.microsoft.com> wrote:[color=green]
> > I'm trying to determine the best way to randomize a set of array items. I'm
> > thinking that I could use an arraylist and have it use the lower and upper
> > bounds as the limits. Any suggestions?[/color]
>
> There's no need to use an ArrayList - the size doesn't need to change.
>
> Here's a method which will actually shuffle *any* IList:
>
> static Random rng = new Random();
> static void Randomize(IList list)
> {
>
> for (int i=list.Count-1; i > 0; i--)
>
> {
> int swapIndex = rng.Next(i+1);
> if (swapIndex != i)
> {
> object tmp = list[swapIndex];
> list[swapIndex] = list[i];
> list[i] = tmp;
> }
> }
> }
>
> The way it works is to mentally divide the list into two halves - the
> unshuffled half (in the range [0,i]) and the shuffled half (in the
> range [i+1, list.Count-1]).
>
> In each iteration, it picks a random element from the unshuffled half,
> and swaps it with the element at the end of the unshuffled half, then
> moves the boundary down.
>
> Note that if you're shuffling arrays of value types, you should use a
> strongly typed version of the above, changing the declaration of both
> list and tmp appropriately, to avoid boxing.
>
> --
> Jon Skeet - <skeet@pobox.com>
>
http://www.pobox.com/~skeet
> If replying to the group, please do not mail me too
>[/color]
