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Re: Newbie Questions [message #25036]

Tue, 15 May 2001 12:21

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

Geoff Herbynchuk <gherbyn@irus.rri.on.ca> writes:

> Hi,
>
> Was just wondering if IDL can have pointers to structures. I'm trying to
> access a variable in the structure with:
>
> if (*info).active_cursor EQ 1) then .....
>
> And I keep getting an error which says "Expression must be a structure in
> this context: <PtrHeapVar57>."
>
> Does anyone know what I'm doing wrong?

Umm, are you sure that INFO points to a structure? I tried it and it
worked fine. (see below). Why not put a "HELP, *INFO, /STRUCT" right
before this statement and see what pops up?

IDL> struct = {active_cursor: 1}
IDL> info = ptr_new(struct)
IDL> help, (*info).active_cursor
<Expression> INT = 1
IDL> help, info
INFO POINTER = <PtrHeapVar1>

Craig

--
------------------------------------------------------------ --------------
Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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[Message index]

		Re: Newbie Questions By: Craig Markwardt on Tue, 15 May 2001 12:21
		Re: Newbie Questions By: Ben Tupper on Tue, 15 May 2001 11:51
		Re: Newbie Questions By: Geoff Herbynchuk on Tue, 15 May 2001 10:17
		Re: Newbie Questions By: Geoff Herbynchuk on Thu, 17 May 2001 05:15

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