Re: [Dev-C++] classes and references

[<or...@vp...>]

Goran Kavrecic wrote:
> try defining your return type as a reference with a simple and(&) after the class name.
> 
> myclass& make_myclass(void)
> {
>    myclass mc_tmp;
>    return mc_tmp;
> }

Well, of course, but this sounds too simple. Besides I have already 
tried it, and it gives a warning: "reference returned to local variable" 
or something.
I am pondering, it has something to do with const stuff.

(... 5 mins trial ...)

BINGO!!!

I have changed the use_myclass function to this:

     static void use_myclass(const myclass& mc){
       printf("Value: %d\n",mc.value);
     }

and it worked!

(... 5 mins reading ...)

YIPEE!!! I have also found the explanation in the book!!! :)))

So: when I call
use_myclass(make_myclass());
then make_myclass() will return with a local variable, thus causing the 
copy constructor to get called. It will make a copy and place into a 
TEMPORARY variable, then pass THAT for use_myclass()
The book sais (rough translation):
"We may use a temporary variable to initialize a constant."
BUT "... a temporary variable *cannot* be used to initialize a 
non-constant reference"

So this is why I didn't work. It tried to initialise the parameter of 
use_myclass(myclass&) (a reference) with a TEMPORARY variable. This is 
illegal.

MSVC and BORLAND *_SUCKS_*!!! They support hacks!!! >:(

My, thank you pal. You drived my attention to the right part! Thanks, 
really! :)

Oh, BTW one should *never* return a reference to a local variable. That 
is written in the book, and it is also understandable. Because it will 
be deleted, before it could be used.

Well, I got cleverer. I think I will be able to handle C++ well. So, 
questions are welcome, least I will look it up, so I will learn too.

And again, thanks for you swift response.

--
Greetings,
   Balázs