Re: Typecasting a class pointer

From:

Antonio Rivas <chanur@telefonica.net>

Newsgroups:

comp.lang.c++

Date:

Wed, 13 Feb 2008 03:56:45 +0100

Message-ID:

<fotm9h$b38$1@nsnmpen2-gest.nuria.telefonica-data.net>

czp.opensource@gmail.com escribi?:

On Feb 13, 9:24 am, Antonio Rivas <cha...@telefonica.net> wrote:

AnonMail2...@gmail.com escribi?:

On Feb 12, 7:42 pm, Antonio Rivas <cha...@telefonica.net> wrote:

I've got a code that is the following way:
classes.h
class claseA {
     public:
         claseA();
         ~claseA();
};
class claseB {
     public:
         claseB();
         claseB( const claseA& aClase);
         ~claseB();
};
main.cpp
#include "classes.h"
int main () {
    claseA* pClaseA = new claseA();
    claseB* pClaseB = new claseB( pClaseA* ); // compiler error
....
    return 0;
};
I get a "expected primary-expression before ')'" error at the marked
line. Seems that try pass a class using a pointer is not valid but when
I try to typecast the dereferenced pointer this way:
classB* pClaseB = new claseB( (claseA)pClaseA* );
I get a different compiler error: "no matching function call to
'claseA::claseA(claseA*&)'
In case this compiler error is a precedence error I tried too the
following code line:
classB* pClaseB = new claseB( (claseA)(pClaseA*) );
but I get again the first compiler error: expected primary-expression
before ')'
Is clear that I'm missing something, or is just that cannot be done this
way?

Use *pClaseA instead of pClaseA* as the argument supplied to the
function call.
HTH

I admit that pointers in C/C++ are quite confusing sometimes. It worked
like a charm. It's clear that I must study much more the topic about
pointers :)

Thank you :)

hi:
claseB( const claseA& aClase);
here means reference, so don't pass a point to it

The problem is that I need pass a pointer since I declare the identifier
as a member of a class and then I initialize the identifier with new in
the constructor of this 3rd class. The reason I do it this way is
because are file I/O classes and to not open/close constantly the file
in each method I open it in the constructor and I close it in the
destructor.