| Help! pointer address return using idl_tools DLM (EXTPROC_DEFINE) [message #38476] |
Thu, 11 March 2004 08:43  |
andy_capax
Messages: 1
Registered: March 2004
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Junior Member |
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Hi
I'm a newbie to Idl. I downloaded the idl_tools DLM library from Ronn
Kling's website http://www.rlkling.com. I"m trying to access from idl
the address of a float pointer returned by a function in C++.
In my C++ program I have:
float* cppfunc(int); //not part of any class
I get the output of the C++ program as sample.dll file using visual
studio 6.0
In Idl I correspondingly use the call:
addr = EXTPROC_DEFINE("idlfunc", "sample.dll", "cppfunc",
"p(i)",/CDECL)
;to get the address of the pointer since the documentation says " If
;the return value is a pointer, the
;memory address returned by the function will be placed in
;an IDL unsigned long and returned to the IDL application."
var = EXTPROC_DEREF(addr, FLOAT = 5)
;to dereference the pointer and copy the data pointed by it to an idl
variable
;it is supposed to copy the 5 float members of the C++ array to var
My problem is this:
addr does not point to a valid memory address, but points to 1 or
0..thus the next step of dereferencing also fails.
I know that it is not a problem with the dll or any such, since
returning a float or an int (not a pointer) works fine using this
approach. I need to pass the address since its a large array and want
to avoid writing my own DLM's for lack of skill.
Can anyone please help? I"m really stuck and dont know what to do..
Thanks all..
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| Re: Help! pointer address return using idl_tools DLM (EXTPROC_DEFINE) [message #38602 is a reply to message #38476] |
Fri, 12 March 2004 03:15  |
mw vogel
Messages: 3
Registered: February 2003
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Junior Member |
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anand wrote:
> Hi
>
> I'm a newbie to Idl. I downloaded the idl_tools DLM library from Ronn
> Kling's website http://www.rlkling.com. I"m trying to access from idl
> the address of a float pointer returned by a function in C++.
> In my C++ program I have:
>
> float* cppfunc(int); //not part of any class
>
> I get the output of the C++ program as sample.dll file using visual
> studio 6.0
>
> In Idl I correspondingly use the call:
>
> addr = EXTPROC_DEFINE("idlfunc", "sample.dll", "cppfunc",
> "p(i)",/CDECL)
> ;to get the address of the pointer since the documentation says " If
> ;the return value is a pointer, the
> ;memory address returned by the function will be placed in
> ;an IDL unsigned long and returned to the IDL application."
>
Ok, my 2 cents :
This _DEFINE call only sets up an internal IDL command that connects to
your function in your DLL. To get valid output, you should actually use
the call. Probably something along the lines of p = idlfunc(0) . Then
use the DEREF to get the values from p.
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