Re: Error when returning a structure pointer

From:
Francis Glassborow <francis@robinton.demon.co.uk>
Newsgroups:
comp.lang.c++.moderated
Date:
30 Jun 2006 17:23:02 -0400
Message-ID:
<NB8MeMD+ynoEFwat@robinton.demon.co.uk>
In article <1151471069.719412.29090@d56g2000cwd.googlegroups.com>, pai
<grpai1@yahoo.com> writes

Hi ,

 The following program gives error can any one solve this.

#include<iostream.h>

struct ab{
       int a;
};

template <class T>
class A{

               struct ab * ret_1();
       public:
               A();
               void disp();
               void ret();

};

template <class T>
void A<T>::ret(){

       struct ab* b;
       b=ret_1();

       return b;
}

template <class T>
struct ab * A<T>::ret_1(){


The above line confuses the compiler. You have used a C'ism by using the
keyword 'struct'. I am not sure whether C++ actually prohibits its use
in this context but I am not surprised that a compiler would be confused
by its, at best redundant, use.

       struct ab* b;
       b=new (struct ab);

       return b;

}

C++ struct names are type names and do not need to be proceeded by
'struct'. Sometimes it is still OK in C++ as a mechanism for unhiding a
name that would otherwise be hidden by a later declaration but even that
should be avoided. If you need to deal with a C compatibility issue,
then use a typedef.

General comment: See how learning C first can cause problems in writing
good idiomatic C++?

--
Francis Glassborow ACCU
Author of 'You Can Do It!' and "You Can Program in C++"
see http://www.spellen.org/youcandoit
For project ideas and contributions:
http://www.spellen.org/youcandoit/projects

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