Compatibility with .NET

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5 total messages Started by Old Wolf Wed, 08 Aug 2007 22:20

#1464

Author: Old Wolf
Date: Wed, 08 Aug 2007 22:20

9 lines
1033 bytes

I want to write a function using C++Builder2006, that
can be called from a third party .NET application.
The function accepts two ascii strings as input,
and returns an ascii string.

What are the requirements for this? My first guess
would be a COM DLL and the function takes
(BSTR*, BSTR, BSTR).

Re: Compatibility with .NET

#1465

Author: Remy Lebeau (TeamB)
Date: Thu, 09 Aug 2007 01:33

13 lines
1207 bytes

"Old Wolf" <oldwolf@inspire.net.nz> wrote in message
news:46ba41a9@newsgroups.borland.com...

> I want to write a function using C++Builder2006,
> that can be called from a third party .NET application.

The only way to do that is to either write a COM object that .NET can load,
or export the function as a C-style function from a DLL that .NET can use
PInvoke to call.


Gambit

Re: Compatibility with .NET

#1466

Author: Old Wolf
Date: Thu, 09 Aug 2007 02:33

14 lines
1486 bytes

"Remy Lebeau \(TeamB\)" <no.spam@no.spam.com> wrote:
>"Old Wolf" <oldwolf@inspire.net.nz> wrote:
>
>> I want to write a function using C++Builder2006,
>> that can be called from a third party .NET application.
>
>The only way to do that is to either write a COM object that .NET
>can load, or export the function as a C-style function from a DLL
>that .NET can use PInvoke to call.

If I go with the latter, then how does memory management
work? My function needs to return a string of characters
to the caller, how should this memory be allocated and freed?

Re: Compatibility with .NET

#1467

Author: David M
Date: Thu, 09 Aug 2007 02:41

18 lines
1643 bytes

> If I go with the latter, then how does memory management
> work? My function needs to return a string of characters
> to the caller, how should this memory be allocated and freed?

Often this is solved by having two methods or being able to call the one 
method twice - the first call calculates how much memory is needed and the 
second uses it.  That way the caller can allocate memory themselves and pass 
the pointer in.

I don't know how this works for .net calling a DLL though, presumably you 
can manually allocate and free memory in unsafe code in .net?

Another option would be to have your DLL return a handle it can then use 
later to free the memory when the caller requests it.

Cheers,

David

Re: Compatibility with .NET

#1468

Author: Remy Lebeau (TeamB)
Date: Thu, 09 Aug 2007 03:00

12 lines
1228 bytes

"David M" <vintagedave@gmail.com> wrote in message
news:46ba7ed5$1@newsgroups.borland.com...

> I don't know how this works for .net calling a DLL though,
> presumably you can manually allocate and free memory in
> unsafe code in .net?

.NET uses PInvoke to execute unmanaged DLL calls.


Gambit

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