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Re: pointer problems [message #66459 is a reply to message #66274]

Fri, 08 May 2009 05:10

tkg
Messages: 2
Registered: May 2009

Junior Member

On May 7, 9:02 pm, "R.G. Stockwell" <noemai...@please.com> wrote:
> <t...@lanl.gov> wrote in message
>
> news:e7dfb99c-91cd-483f-93ba-9e13c31f659a@y33g2000prg.google groups.com...
>
>
>
>
>
>> I'm trying to store an array of pixel xy indicies for later output to
>> a text file. The number of xy pairs is different for each array
>> element. I'm trying to use pointers to do this with the following
>> code snippet:
>
>> xy = ptrarr(npixels, /ALLOC)
>
>> for ipixel = 0, npixels - 1 do begin
>
>> ; much snipped code
>
>> indi = where(superMask ne 0, count)
>
>> if (count gt 0) then *xy[ipixel] = array_indices(superMask,
>> indi)
>
>> ; more snipped code
>
>> endfor
>
> You need an else branch to assign the values of
> *xy in the case where count is = 0.
>
> Or else, accessing xy in the future can result in
> "variable is undefined" error messages.
>
> cheers,
> bob

I saw that possibility and changed the code, but count
doesn't have a 'zero' case in the test data I've used so far.
Something else is causing the "variable is undefined" message.
If this were a C program, I'd suspect a buffer overrun, but,
being relatively new to IDL programming, I don't know how to
avoid that in IDL.

Thanks,
Tom

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[Message index]

		pointer problems By: tkg on Thu, 07 May 2009 11:55
		Re: pointer problems By: R.G. Stockwell on Fri, 08 May 2009 11:20
		Re: pointer problems By: tkg on Fri, 08 May 2009 05:10
		Re: pointer problems By: R.G. Stockwell on Thu, 07 May 2009 20:02

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