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Re: Some MAKE_DLL questions [message #92143 is a reply to message #92142]

Mon, 19 October 2015 18:40

Jim Pendleton
Messages: 165
Registered: November 2011

Senior Member

On Monday, October 19, 2015 at 11:36:39 AM UTC-6, nata wrote:
> Thank you Michael for your reply!
>
> About my third question; I just want to know if the variables are copied (duplicated) when they are passed to the C code.
> Thank you,
> Nata

By default, scalar arguments are passed by reference. There's a VALUE keyword to CALL_EXTERNAL to control this. Arrays are always passed by reference.

Strings in particular are a special case. You'll want to understand the differences. (It's generally easier to convert them to byte arrays instead and cast the pointers to char * on the C side.)

As the online help says, "See Chapter 3, "Using CALL_EXTERNAL" (External Development Guide in the help/pdf directory of your IDL installation).

Jim P

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[Message index]

		Some MAKE_DLL questions By: natha on Mon, 19 October 2015 06:30
		Re: Some MAKE_DLL questions By: Russell[1] on Mon, 19 October 2015 08:04
		Re: Some MAKE_DLL questions By: natha on Mon, 19 October 2015 08:44
		Re: Some MAKE_DLL questions By: Michael Galloy on Mon, 19 October 2015 09:58
		Re: Some MAKE_DLL questions By: natha on Mon, 19 October 2015 10:36
		Re: Some MAKE_DLL questions By: Jim Pendleton on Mon, 19 October 2015 18:40
		Re: Some MAKE_DLL questions By: natha on Tue, 20 October 2015 08:13

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