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Re: CALL_EXTERNAL and memory allocation [message #29700 is a reply to message #29694]

Sat, 09 March 2002 09:42

Mark Rivers
Messages: 49
Registered: February 2000

Member

lyubo <lzagorch@cs.wright.edu> wrote in message
news:a6d9nn$76k$1@mercury.wright.edu...
> I have to get back a string from C, and if I have a null string
> defined in IDL and passed to C it won't work, because there
> isn't any memory allocated to the string.
>
> In general, how can I allocate memory for a string in IDL?

I would recommend not passing strings to CALL_EXTERNAL, but rather pass a
byte array, it's easier and more portable, since the IDL string structure
definition changed between IDL 5.4 and 5.5.

In your wrapper routine.

b = bytarr(256) ; Must dimension for maximum string length
s = call_external('my_dll', 'my_funct', b)
; The external C routine places the string in the bytarr 'b', with NULL
termination.
str = string(b) ; Convert from bytarr to string

Mark Rivers

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[Message index]

		Re: CALL_EXTERNAL and memory allocation By: Michael Zingale on Mon, 11 March 2002 10:03
		Re: CALL_EXTERNAL and memory allocation By: James Kuyper on Mon, 11 March 2002 08:43
		Re: CALL_EXTERNAL and memory allocation By: Michael Zingale on Sun, 10 March 2002 15:43
		Re: CALL_EXTERNAL and memory allocation By: Michael Zingale on Sun, 10 March 2002 13:42
		Re: CALL_EXTERNAL and memory allocation By: Mark Rivers on Sat, 09 March 2002 09:42

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