| Array has a corrupted discriptor, reliable? [message #61696] |
Mon, 28 July 2008 03:24  |
Joost Aan de Brugh
Messages: 16
Registered: July 2008
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Junior Member |
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Hello folks,
I am using IDL in corporation with Fortran and I am using arrays of
variable size. Because I am in the initial stage of the program, I
might make mistakes and have Fortran write data outside of my arrays.
A simple example:
idlarray = FltArr(OneTooFew)
Call_External,.... (writng outside the idlarray bounds)
....
End
And I get a corrupted discriptor and the End in IDL. I was expecting a
Segmentation fault, because I write data on a location that I have not
allocated.
Will I always get an error if I have Fortran write outside of my
bounds or do I take the risk that I write data on wrong places without
noticing?
(This time, I am glad if I see an error message).
Greetings,
Joost Aan de Brugh
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| Re: Array has a corrupted discriptor, reliable? [message #61747 is a reply to message #61696] |
Tue, 29 July 2008 09:01  |
Joost Aan de Brugh
Messages: 16
Registered: July 2008
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Junior Member |
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On Jul 29, 3:50 pm, Norbert Hahn <ihates...@nospam.invalid> wrote:
> Some Fortran compilers allow range checking with arrays as a compile
> time option. If your compiler support this function you'll get an
> error condition within the Fortran program. However, I don't know
> how to handle errors within Fortran code.
>
> Norbert
Unfortunately, I don't know that much of Fortran as well. I use
%val(argv(..)) in Fortran to convert from memory address to value, but
Fortran has no clue what data type in in there. So if I put an integer
varibale with value '2' and give it to Fortran. And I use Call
routine(%val(argv(1)) and in the routine the variable is defined as a
real, it becomes a stupid value corresponding to the only the second
bit set (or however the integer '2' is stored).
The same way I can pass whole arrays. For example, if I give the
memory address of a 10-element floatarray and in Fortran i Call
routine(%val(argv(1))) and the the corresponding variable in the
routine is a Real, Dimension(10), it works fine. For safety, I might
as well pass the 10 as an integer from IDL to Fortran so that Fortran
knows that there are 10 elements.
But if someone with humour sets the flag -fdefault-real-8 at the
Fortran compiler somewhere in an obscure Makefile, Fortran will think
it is a double array, taking five values constructed somehow from my
floatarray and the next 40 bytes in memory. This though Fortran still
thinks that the array is 10 elements long and there is no problem as
long as the computer allows me to write (or read) from the 40 extra
bytes (God knows what is in there).
In my first example, I was expecting a segmentation fault caused by
Fortran and not the nice little "Array has a corrupted discriptor".
But now it looks like solved, since I tried this example (Fortran
thinking they are doubles while they are floats) and I get my desired
Segmentation fault.
Kind regards,
Joost Aan de Brugh
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| Re: Array has a corrupted discriptor, reliable? [message #61756 is a reply to message #61696] |
Tue, 29 July 2008 06:50 |
Norbert Hahn
Messages: 46
Registered: May 2003
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Member |
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Joost Aan de Brugh <joostadb@gmail.com> wrote:
> Hello folks,
>
> I am using IDL in corporation with Fortran and I am using arrays of
> variable size. Because I am in the initial stage of the program, I
> might make mistakes and have Fortran write data outside of my arrays.
Some Fortran compilers allow range checking with arrays as a compile
time option. If your compiler support this function you'll get an
error condition within the Fortran program. However, I don't know
how to handle errors within Fortran code.
Norbert
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