🚀 go-pugleaf

Emmanuel Derriey a �crit dans le message <7blh68$646$1@ai.alienor.fr>...
>Hi !
>I think that your procedure is :
>procedure ProcedureInsideTheDLL (Input:String; var Output:String);
>and not
>procedure ProcedureInsideTheDLL (Input:String; Output:String);

In fact... d'oh!

>Nevertheless, you should use PChar arguments ; you must consider that the
>PChar are allocated by the caller.
>Example :
>procedure ProcedureInsideTheDLL (PcharInput:PChar; PCharOutput:PChar);
//
>Don't need the 'var' keyword because it's a allocated pointer
>var
>  Input : string;
>  Output : string
>begin
>  Input := string(PCharInput);    // string and PChar are compatible
>// Do something
>  PCharOutput := PChar(Output);
>end;
>It should work if enought char are allocated in PCharOutput !!! Else : BOOM
>!
>Hope it will help you...


It does!

But one more question:

When I'm calling this procedure, what will I use? Something like:

ProcedureInsideTheDLL (PChar(Input); PChar(Output));
where Input, Output: String;

But it is possible that I will pass very long strings that way (like more
than 1MB)... so I'm concern about memory here:

PChar is a pointer? Right? So the DLL procedure will manipulate a shared
copy from the calling app. But when using PChar(MyString), am I making
actually a copy of my string?

And of course, inside the DLL, when using:

>  Input := string(PCharInput);

...I'm making yet another copy...

If my original string is 10MB long, I don't want, if possible, to use 20 or
30MB of RAM...

The main question here is: does PChar(String) gives a pointer to String, or
does it makes a C string copy of the original Pascal string (long string).

>--
>Emmanuel Derriey.
>Windows Software Developer.
>
>e-mail : ederriey@at-iris.com


Thanks again,

Louis Pelletier, Qu�bec.