| Re: When Ptr_New doesn't work [message #28950 is a reply to message #28949] |
Tue, 22 January 2002 09:36   |
Richard Younger
Messages: 43
Registered: November 2000
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Member |
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Hi, Carles.
There's something very fishy here. Your code seems perfectly correct to
me. I found that when the outer set of parenthesis on the left hand
side of the offending line of code is omitted, your program snippet
seems to work fine. When I include the outer set of parenthesis, it
gives me an error on versions Win 5.3-5.5, and possibly earlier. My
test program is below. Either this is a bug or a very strange quirk of
the language with obscure origins. Perhaps it should be reported?
For anyone else out there running on different systems, do other
versions have this problem?
Best,
Rich
--
PRO test
nElems = 4
elems = intarr(nElems)+2
rCoefficients=PtrArr(nElems)
FOR i=0, nElems-1 DO BEGIN
rCoefficients[i]=Ptr_New(PtrArr(elems[i]))
ENDFOR
FOR j=0, nElems-1 DO BEGIN
FOR k=0, elems[j]-1 DO BEGIN
;Works:
(*rCoefficients[j])[k] = Ptr_New(FltArr(2), /NO_COPY)
;Causes Error:
;((*rCoefficients[j])[k]) = Ptr_New(FltArr(2), /NO_COPY)
ENDFOR
ENDFOR
;;--- Clean up ----
;; - as in "I don't do any".
END
--
Richard Younger
Carles Badenes wrote:
>
> I have the following problem:
>
> rCoefficients=PtrArr(nElems)
> FOR i=0, nElems-1 DO BEGIN
> rCoefficients[i]=Ptr_New(PtrArr(elems[i]))
> ENDFOR
>
> since elems is a vector of integers, each element i of
> rCoefficients is a pointer to an array of elems[i] pointers.
> But, for some reason,
>
> ((*rCoefficients[j])[k]) = Ptr_New(FltArr(2), /NO_COPY)
>
> doesn't work. k and j are within the allowed range, of course, and
> ((*rCoefficients[j])[k]) is a null pointer, as expected from the
> initialization above. Ptr_New is supposed to allocate memory for the
> specified pointer to store an array of 2 floats, but I get the message
>
> Expression must be named variable in this context: <POINTER
> (<NullPointer>)>.
>
> I must be doing something wrong. Can you help?
>
> Thanks,
> Carles
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