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Re: Inside rectangle [message #31336 is a reply to message #31330]

Tue, 02 July 2002 14:49

Rick Towler
Messages: 821
Registered: August 1998

Senior Member

"Neil Talsania" <neil.talsania@kodak.com> wrote > Now I think I want to make
a structure to hold the 4 corner coordinates.
> Then I need to create an array of these structures, but I want that array
to
> be able to grow. Then I will loop through that array (For loop) calling a
> function that will check to see if the point is inside the coordinates.
>
> So the crux of my problem ( I think) is that I need the array size to
> increase every time the user adds a set. But I dont know ho to do this.

Reimar's suggestion will work but if you are carting this data around your
application in a structure, at some point you'll want to use a pointer to
reference your array of structures.

But better yet, why not use a linked list? Then you can easily add and
remove individual rectangles and not have to deal with the details. You can
download David Fanning's linkedlist__define.pro from his website
(www.dfanning.com). Since the linked list is an object it is simple to cart
around in a structure. His object returns a pointer to the data contained
in a node and you will need to be aware of precedence when dereferencing the
pointer:

imagine 'll' is my linked list object with all of my rectangle structures I
can get a pointer 'p' to the first structure in the list:

p = ll->get_item(0)

To get the data that the pointer refers to I need to use parentheses to
ensure that IDL dereferences the pointer p before trying to access the
structure elements:

IDL> print,(*p).coord
0.000000 0.000000 0.000000 0.000000

-Rick

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[Message index]

		Re: Inside rectangle By: Pavel A. Romashkin on Wed, 03 July 2002 10:28
		Re: Inside rectangle By: Rick Towler on Tue, 02 July 2002 14:49
		Re: Inside rectangle By: btupper on Tue, 02 July 2002 11:58
		Re: Inside rectangle By: R.Bauer on Tue, 02 July 2002 10:40

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