Error Conversion To Inaccessible Base Class Is Not Allowed

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Expected Class Name Before Token Inheritance

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Can Protected Class Be Inherited

a minute: Sign up C++ inheritance - inaccessible base? up vote 75 down vote favorite 10 I seem to be unable to use a base class as a function parameter, have I messed up my inheritance? I have the following in my main: int some_ftn(Foo *f) { /* some code */ }; Bar b; some_ftn(&b); And the class Bar inheriting from c++ inheritance private Foo in such a way: class Bar : Foo { public: Bar(); //snip private: //snip }; Should this not work? I don't seem to be able to make that call in my main function c++ inheritance share|improve this question edited Nov 27 '11 at 8:30 aaaidan 3,39933875 asked Jan 31 '11 at 2:19 bandai 395146 add a comment| 2 Answers 2 active oldest votes up vote 139 down vote accepted You have to do this: class Bar : public Foo { // ... } The default inheritance type of a class in C++ is private, so any public and protected members from the base class are limited to private. struct inheritance on the other hand is public by default. share|improve this answer edited Jul 17 '15 at 15:06 Barry 101k10129274 answered Jan 31 '11 at 2:22 Andrew Noyes 2,99111013 add a comment| Did you find this question interesting? Try our newsletter Sign up for our newsletter and get our top new questions delivered to your inbox (see an example). Subscribed! Success! Please click the link in the confirmation email to activat

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C++ Public Inheritance Private Members

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C++ Public Vs Private Vs Protected

Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like error: is an inaccessible base of you, helping each other. Join them; it only takes a minute: Sign up Inheritance: 'A' is an inaccessible base of 'B' up vote 49 down vote favorite 11 $ cat inheritance.cpp #include using namespace std; class http://stackoverflow.com/questions/4847100/c-inheritance-inaccessible-base A { }; class B : private A { }; int main() { A* ab = new B; } $ $ g++ inheritance.cpp inheritance.cpp: In function 'int main()': inheritance.cpp:9: error: 'A' is an inaccessible base of 'B' $ I just do not understand this error. As I understand, and as this tutorial confirms, private inheritance should only change how the members of class B are visible to the outside world. I think the private specifier http://stackoverflow.com/questions/9661936/inheritance-a-is-an-inaccessible-base-of-b is doing more than just change visibility of class B members here. What do I get this error and what does it mean? Basically what is wrong with allowing this type of code in C++? Looks totally harmless. c++ inheritance share|improve this question asked Mar 12 '12 at 4:55 Lazer 25k66211309 add a comment| 5 Answers 5 active oldest votes up vote 64 down vote accepted By making the inheritance private, you're basically saying that even the fact that B inherits from A (at all) is private -- not accessible/visible to the outside world. Without getting into a long-winded discussion of what would happen if it was allowed, the simple fact is that it's not allowed. If you want to use a pointer to base to refer to an object of derived type, then you're pretty much stuck with using public inheritance. Edit: Since somebody went to the trouble of sending an email to ask for more information about what could happen if this was allowed, I guess I'll elaborate a little on it. The basic problem is that private inheritance is not necessarily intended to follow the Liskov substitution principle. Public inheritance asserts that a derived object can be substituted for an object of the base class, and proper semantics will still result. Private inheritance does not assert that though. The usual de

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Post your question and get tips & solutions from a community of 418,509 IT Pros & Developers. It's quick & easy. inaccessible base despite public inheritance P: n/a Stefan Weber Hi, I have the following header file (named test.h): class Foo { public: Foo(void) {} virtual ~Foo(void) {} }; class Bar : public Foo { public: Bar(void) {} virtual ~Bar(void) {} }; with a very simple cpp file: #include "test.h" int main() { Foo* f = new Bar(); } This compiles with Visual Studio 2005, but with g++ 4.1.1 I get an error: bash-3.00$ test.cpp:4: error: Foo is an inaccessible base of Bar Acutally, I know that this error message occurs when doing something like "class Bar : private Foo" (i.e. inherit the code but withouth polymorphism). But I obviously declared to use public inheritance. Does anybody see the problem? Thanks, Stefan May 22 '07 #1 Post Reply Share this Question 9 Replies P: n/a Victor Bazarov Stefan Weber wrote: I have the following header file (named test.h): class Foo { public: Foo(void) {} virtual ~Foo(void) {} }; class Bar : public Foo { public: Bar(void) {} virtual ~Bar(void) {} }; with a very simple cpp file: #include "test.h" int main() { Foo* f = new Bar(); } This compiles with Visual Studio 2005, but with g++ 4.1.1 I get an error: bash-3.00$ test.cpp:4: error: Foo is an inaccessible base of Bar Acutally, I know that this error message occurs when doing something like "class Bar : private Foo" (i.e. inherit the code but withouth polymorphism). But I obviously declared to use public inheritance. Does anybody see the problem? The only /potential/ problem is the name of the header file. Put the code you posted in the same cpp file and compile it again (comment out 'with a very...' and the '#include'). If it compiles, the problem isn't in the code. If it doesn't, you're SOL. Get a better compiler. V -- Please remove capital 'A's when replying by e-mail I do not respond to top-posted replies, please don't ask May 22 '07 #2 P: n/a Howard "Stefan Weber"