ans1) By default, all members of a class declared with the class
keyword have private access for all its members. Therefore, any member
that is declared before one other class specifier automatically has
private access. thats why your code is producing error if u comment the public 
keyword

ans2)who says that pa is pointing anything.It is pointing to somewhere. but you 
see it can create problems in further program.
--- On Wed, 6/18/08, frankzhu_2001 <[EMAIL PROTECTED]> wrote:
From: frankzhu_2001 <[EMAIL PROTECTED]>
Subject: [c-prog] class composition
To: [email protected]
Date: Wednesday, June 18, 2008, 7:56 PM










    
            Hi,

I have two questions,

1. The following program will not compile if the 'public' is not 

defined. why?

2. Since pa is pointed to nowhere, is it a safe to use pa without 

the instanciate the class a?



thanks,



--- code starts here ---



#include<iostream>



using namespace std;

class a{

        public:

                void print(void) { cout << "a print\n";}

};

class b{

        public:  // error if this line is commented out.

        a* pa;

};



int main(void)

{



        b b1;

        b1.pa->print( );

}




      

    
    
        
         
        
        








        


        
        


      

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