Re: [Dev-C++] ostringstream and insertion operator problem

[Jonathan W. <jon...@gm...>]

Hi,

Well technically the compiler handles the reference part, so you would have
to return an object, and the compiler would make that a reference.... So I'm
not sure how this NULL thing pans out in the end...

Ok well it seems I misleaded you...

>From here: http://www.cppreference.com/cppio/examples.html

"""Simply evaluating an I/O object in a boolean context will return false if
any errors have occurred:"""

Which is actually whet the test was all about.

Sorry about that,
Jonathan

On 11/2/07, A D <a_...@ho...> wrote:
>
>
> Thanks for your reply.
>
>
> > Jonathan wrote:
> > A reference to an object is actually a pointer, which is a number (to
> which
> > we have attached a special meaning)
> > Testing this reference tests the pointer with 0, or NULL. I think you
> will
> > find that << returns NULL if it fails.
>
> Still it's not clear to me. So you are sayin' that a function that returns
> a reference
> type can return NULL for that same purpose. Suppose there's a code like
> this:
>
> #include
>
> class Aa
> {
>    public:
>    int i;
>    Aa& aFunc();
> };
>
> Aa& Aa::aFunc()
> {
>    return NULL;
> }
>
> int main()
> {
>    Aa firstObj;
>
>    firstObj.aFunc();
>    return 0;
> }
>
> aFunc() function supposed to return NULL. But i get the following
> compilation
> error:
>
> test.cc: In member function 'Aa& Aa::aFunc()':
> test.cc:13: error: invalid initialization of non-const reference of type
> 'Aa&'
> from a temporary of type 'int'
>
> if a function can return a NULL value instead of a reference value why
> this code
> and this function spewing this error?
>
>
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