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Re: structure arguments sometimes behave like value types - why? [message #53604 is a reply to message #53603]

Fri, 20 April 2007 14:26

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

justspam03@yahoo.de writes:

> according to the IDL reference, structures (as a whole) are treated
> like reference types when supplied as an argument. A small test
> program of the kind
> confirms this - after the call to changeval, a.value has value '4'.
> However, when the structure is an object variable as in the example
> appended below, it seems that only a copy of structtest.val is
> exchanged, not a reference to it. The final call to printValue in
> 'main' prints a '1'.
> Could someone please explain why?

In one case you are passing an IDL variable, which is passed
by reference. In the other you are passing a structure reference,
which is NOT an IDL variable, and like everything else that is NOT
an IDL variable, is passed by value:

http://www.dfanning.com/tips/read_subscripted_array.html

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: structure arguments sometimes behave like value types - why? By: justspam03 on Fri, 20 April 2007 13:36
		Re: structure arguments sometimes behave like value types - why? By: David Fanning on Fri, 20 April 2007 14:26
		Re: structure arguments sometimes behave like value types - why? By: justspam03 on Fri, 20 April 2007 13:26
		Re: structure arguments sometimes behave like value types - why? By: JD Smith on Mon, 23 April 2007 10:31

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