C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  what is private inheritance          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message MJ Guest Posted: Fri Apr 29, 2005 2:10 pm    Post subject: what is private inheritance Hi I have a following sample code class base and class derived. I have inherited the base class as private and tried to compile the code its giving an error "conversion from 'class derived *' to 'class base *' exists, but is inaccessible" If I inherit using public it works well ... I am not very clear about the private inheritance I will be happy if someone can guide me ... when shall I use public, private and protected inheritance ------------------------------------------------------- #include<iostream> using namespace std; class base{ public: int b; virtual f(){ cout << " base" << endl;} }; class derived:private base{ public: int d; f() { cout << " derived" << endl; } }; int main () { derived *d = new derived; d->f(); base *b; b = d; int a; cin >> a; return 0 ; } ------------------------------------------------------- Regards MJ... Back to top Victor Bazarov Guest Posted: Fri Apr 29, 2005 2:18 pm    Post subject: Re: what is private inheritance MJ wrote: Quote: I have a following sample code class base and class derived. I have inherited the base class as private and tried to compile the code its giving an error "conversion from 'class derived *' to 'class base *' exists, but is inaccessible" If I inherit using public it works well ... I am not very clear about the private inheritance I will be happy if someone can guide me ... when shall I use public, private and protected inheritance Private and protected inheritance are not to be used in the situation that requires "is-a" relationship. Otherwise, private and protected inheritance is just the same as declaring members private or protected. Private ones are only accessible to members and friends, and protected ones are accessible to members, friends, and classes that derive from this one. Think of the base class as a member of the class that derives from it. Anything related to that "member" should follow the rules of access qualifiers. Conversions from derived to base is part of that "anything". V Back to top codigo Guest Posted: Fri Apr 29, 2005 8:01 pm    Post subject: Re: what is private inheritance "MJ" <mayurdjain (AT) gmail (DOT) com> wrote Quote: Hi I have a following sample code class base and class derived. I have inherited the base class as private and tried to compile the code its giving an error "conversion from 'class derived *' to 'class base *' exists, but is inaccessible" If I inherit using public it works well ... I am not very clear about the private inheritance I will be happy if someone can guide me ... when shall I use public, private and protected inheritance Private inheritence is usually a form of composition. The resulting class has the functionality and members of the base class (but that functionality is hidden inside the base). Unlike public or protected inheritence, you can't state that the derived type is_a base type. This relationship is usually described as: The Derived class in_terms_of the base class. #include <iostream> using std::cout; using std::endl; class Base { int b; public: Base(int n): b(n) { } virtual ~Base() { } void f() const { cout << "(base) b = " << b; } }; class Derived : private Base { int d; public: Derived(int n, int m) : Base(n), d(m) { } ~Derived() { } void f() const { cout << "(derived) d = " << d; cout << endl; Base::f(); cout << endl; } }; int main() { Derived *d = new Derived(100, 10); d->f(); delete d; return 0 ; } Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         C++Talk.NET Forum Index -> C++ language (comp.lang.c++) All times are GMT Page 1 of 1   Jump to: Select a forum C/C++----------------C LanguageC Language (Moderated)C++ Language (Moderated)C++ language (comp.lang.c++)C++ language, library and standards Non-English C/C++ Newsgroups----------------C++ (German)C++ (French)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.