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C++ Discussion Thread
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Oct 11th, 2005

private inheritance

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I may not be understanding private inheritance right, but I thought when you inherited privately that you could still access public member data/functions, but the child class of the derived class would not. For some reason it is saying the public print() method is not accessable in this context....Is there something I'm doing wrong?

C++ Syntax (Toggle Plain Text)
#include <iostream>
#include <cstdlib>
 
class Animal
{
      public:
             Animal() { std::cout << "Animal Constructor....\n"; }
             virtual ~Animal() { std::cout << "Animal Deconstructor...\n"; }
 
             void print() const { std::cout << "Print method...\n"; }
      private:
              void printP() const { std::cout << "Private print method...\n"; }
};
 
 
class Dog : public Animal
{
      public: 
              Dog() { std::cout << "Dog constructor...\n"; }
              ~Dog() { std::cout << "Dog deconstructor..\n"; }
};
 
class Bird : private Animal
{
      public:
             Bird() { std::cout << "Bird constructor...\n"; }
             ~Bird() { std::cout << "Bird deconstructor...\n"; }
};
 
 
 
int main()
{
    Bird b;
    b.print();
}
#include <iostream>
#include <cstdlib>

class Animal
{
      public:
             Animal() { std::cout << "Animal Constructor....\n"; }
             virtual ~Animal() { std::cout << "Animal Deconstructor...\n"; }
             
             void print() const { std::cout << "Print method...\n"; }
      private:
              void printP() const { std::cout << "Private print method...\n"; }
};


class Dog : public Animal
{
      public: 
              Dog() { std::cout << "Dog constructor...\n"; }
              ~Dog() { std::cout << "Dog deconstructor..\n"; }
};

class Bird : private Animal
{
      public:
             Bird() { std::cout << "Bird constructor...\n"; }
             ~Bird() { std::cout << "Bird deconstructor...\n"; }
};



int main()
{
    Bird b;
    b.print();
}

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Need example of how to use INHERITANCE! in C++

server_crash

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Postaholic

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since Jun 2004

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Oct 11th, 2005

Re: private inheritance

your compiler is correct. print() is not accessible outside Bird class because of private inherentence. It can only be called from within Bird class just like any other private member.

Ancient Dragon

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Online

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Oct 11th, 2005

Re: private inheritance

I'm using bloodshed....It's giving me the same error but I don't understand why. Is it not legal for me to do this?

server_crash

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Postaholic

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since Jun 2004

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Oct 11th, 2005

Re: private inheritance

no its not legal. because you have used private inheritance your class now looks like this.....

C++ Syntax (Toggle Plain Text)
class Bird
{
   public:
      Bird();
      virtual ~Bird();
   private:
      void Print()const;
};
class Bird
{
   public:
      Bird();
      virtual ~Bird();
   private:
      void Print()const;
};

now do you see why your code fails.

Stoned_coder

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Junior Poster

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since Jul 2005

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Oct 11th, 2005

Re: private inheritance

I see now why it didn't compile, but what's the purpose of private inheritance? Is it impossible to implement that method?

server_crash

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Postaholic

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since Jun 2004

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Oct 11th, 2005

Re: private inheritance

private inheritance has its uses. It is similar in effect to composition and nothing like public inheritance. When you become more familiar with c++, you will often find uses for private inheritance.

Stoned_coder

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Junior Poster

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Oct 11th, 2005

Re: private inheritance

http://www.parashift.com/c++-faq-lit...heritance.html

Dave Sinkula

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long time no c

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since Apr 2004

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Aug 12th, 2010

Re: private inheritance

since Print P function is declared as private in base class, u can not acess that function even if u inherit it as public.
now make print p function as public in base class and using Animal::printP will solve u r problem

brkurre

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