Computer Science Canada

2D Arrays, or Something?
Author:  [Gandalf] [ Mon Jun 20, 2005 4:21 pm ]
Post subject:  2D Arrays, or Something?
I'm just a bit confusled right now, having an exam and the sort tomorrow.
Let's say I had this:
code:
var bullet : flexible array 1 .. 0 of
    record
        x, y
    end record

How would I add a say, bullet(2) so that I don't have to copy the whole thing and rename the new bullet to bullet2. So pretty much what I'm asking is, how would I shorten something like this:
code:
var bullet : flexible array 1 .. 0 of
    record
        x, y : real
    end record

var bullet2 : flexible array 1 .. 0 of
    record
        x, y : real
    end record

Thanks.
Author:  Bacchus [ Mon Jun 20, 2005 4:39 pm ]
Post subject: 
Ok, now I'm a bit confusled about what you mean. Do you mean like a shorter way of making another array with the same record?
Turing:
type positions :
    record
        x, y : real
    end record
var bullet : flexible array 1 .. 0 of positions
var bullet2 : flexible array 1 .. 0 of positions
Or do you mean adding another bullet to your array?
Turing:
var bullet : flexible array 1 .. 0 of
    record
        x, y : real
    end record
new bullet, 2
Or do you mean like adding another dimension to the flexible array? Please explain a bit more.
Author:  lyam_kaskade [ Mon Jun 20, 2005 4:40 pm ]
Post subject: 
code:

type foo :
    record
        x, y : int
    end record

var bullet : flexible array 1 .. 0 of foo
var bullet2 : flexible array 1 .. 0 of foo
[/code]
Author:  Cervantes [ Mon Jun 20, 2005 4:41 pm ]
Post subject: 
Well, you can make it into a type and then create different variables:
code:

type obj :
     record
         x, y, : real
     end record
var bullet : flexible array 1 .. 0 of obj
var bullet2 : flexible array 1 .. 0 of obj

But if you've got a flexible array of bullets, why are you making bullet and bullet2? In any case, if you must do that, you could try a 2D array.
code:

type obj :
    record
        x, y : real
    end record
var bullet : flexible array 1 .. 0, 1 .. 0 of obj

EDIT: 2 posts got there before me. Yee-gawds!
Author:  [Gandalf] [ Mon Jun 20, 2005 5:05 pm ]
Post subject: 
Ya, thanks - I was forgetting about types Doh!

Quote:
But if you've got a flexible array of bullets, why are you making bullet and bullet2?

Well, they're not two different bullets, they're two kinds of bullets going in different directions.
Author:  MysticVegeta [ Mon Jun 20, 2005 6:35 pm ]
Post subject: 
doh! there can be a flexible array with mutiple dimension, jeez and all this time i have been sleeping Very Shocked
Author:  Cervantes [ Mon Jun 20, 2005 6:53 pm ]
Post subject: 
I was pressured into adding that to the tutorial. Check it out Smile
Author:  Bacchus [ Mon Jun 20, 2005 9:38 pm ]
Post subject: 
Even though in your Tutorial Cervantes, you list some basic rules... Like
Quote:
In a 2D array, if you leave one upper bounds alone, you can do whatever you want to the other bounds.
That doesn't work Sad Try it out:
code:
var foo:flexible array 1..3,1..2 of int
new foo,3,3
There is a bit of a way around this, takes up a bit of space thought. Just create a new array (doesn't have to be flexible) and store the orginal array in that then change the dimension to 0 and back to what you want before restoring the original array's values. lol
Author:  Cervantes [ Tue Jun 21, 2005 9:56 am ]
Post subject: 
Ooh, thanks for that, Bacchus. It's updated. Smile
Author:  MysticVegeta [ Tue Jun 21, 2005 11:05 am ]
Post subject: 
Bacchus wrote:
Just create a new array (doesn't have to be flexible) and store the orginal array in that then change the dimension to 0 and back to what you want before restoring the original array's values. lol


i see i see, pretty nifty.I think the reason they cant make it 3, 3 is because turing doesnt know the flexiblility of the elements of each of the dimensions of the flexible array.
Author:  Cervantes [ Tue Jun 21, 2005 1:07 pm ]
Post subject: 
Bah! This is not so pretty!
Turing:

var list : flexible array 1 .. 3, 1 .. 2 of int
for i : 1 .. upper (list, 1)
    for j : 1 .. upper (list, 2)
        list (i, j) := i * j
    end for
end for

var tempArr : array 1 .. upper (list, 1), 1 .. 4 of int
for i : 1 .. upper (tempArr, 1)
    for j : 1 .. upper (tempArr, 2)
        if i <= upper (list, 1) & j <= upper (list, 2) then
            tempArr (i, j) := list (i, j)
        else
            tempArr (i, j) := minint %flag
        end if
    end for
end for

new list, upper (list, 1), 0
new list, upper (list, 1), upper (tempArr, 2)
for i : 1 .. upper (list, 1)
    for j : 1 .. upper (list, 2)
        %if tempArr (i, j) ~= minint then
            list (i, j) := tempArr (i, j)
        %end if
    end for
end for

for i : 1 .. upper (list, 1)
    for j : 1 .. upper (list, 2)
        put list (i, j)
    end for
end for

I wanted to make a procedure of it, but it's a syntax error to do this:
code:

proc foo (var arr : flexible array 1 .. *, 1 .. * of int)


Gandalf, my apologies for taking over your thread. I'll leave if you want. Crying or Very sad
Author:  [Gandalf] [ Tue Jun 21, 2005 1:19 pm ]
Post subject: 
No, it's alright Smile. You always learn new things, and these kinds of discussions are useful. Trying to do what Turing cannot accept, using Turing Smile. Maybe you'll even come up with something for Stargates project.

Besides, its nice to have a long topic!

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