Re: C++ Structure

["Ron Nanko" <RonNanko@gm-squared.de>]

> lachat wrote:
> >
> >   BruitageInfos                  MyBruitage;
>
> I assume you meant to type:
>
>     BruitageInfos* MyBruitage;
>
> Because you mention that this:
>
> >   MyBruitage = (BruitageInfos2  *)  malloc( sizeof(BruitageInfos2) );
>
> works.

The above DOESN'T work, of course, for 'MyBruitage' is a pointer to a
BruitageInfos structure, thus making the assignment invalid.

> >   MyBruitage->DSBuffer->Stop();
> >
> >   It's as if the compiler doesn't know what "MyBruitage" refers to !!
>
> It does know, but you're skipping a level of indirection.  MyBruitage is a
> pointer, not a structure.  Before you can access your DSBuffer member of
the
> structure you've defined, you need to dereference your pointer to tell the
> compiler what exactly you are doing.
>
> What you are trying to do should look like this:
>
>      (MyBruitage *).DSBuffer->Stop();

Actually it should look like this, assuming that a valid 'BruitageInfos' -
pointer:

(*MyBruitage).DSBuffer->Stop();

However, this is no solution for the problem, as we're not able to use the
above assignment. You could use something like the following example:

#include <iostream.h>

struct Test
{
 int a;
};

struct Test2
{
 int b;
};

void main()
{
 // create generic pointer
 void *test;

 test = new (Test);
// or test = new(Test2);

 // explicit conversion to Test*
 ((Test *)test)->a = 10;
// or ((Test2 *)test)->b = 10

 cout << ((Test *)test)->a << "\n";
// or cout << ((Test2 *)test)->b << "\n";

 // free memory again
 delete (test);
}

There's no way around this, if you want to work with generic pointers.

Ciao,
Ron Nanko
chief coder, gm²

Ceterum censeo Carthaginem esse delendam.

Ron Nanko, department of computer science, university of Kiel, Germany
contact me at rna@informatik.uni-kiel.de (university), ICQ #24926976,
RonNanko@gm-squared.de (private), or http://www.RonNanko.de
Visit my game development company at http://www.gm-squared.de



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