Thread: problem with polymorphism

  1. #1
    Registered User
    Join Date
    Sep 2007

    problem with polymorphism

    Hi guys, I had created a base class and its derived class, and Both the base class have a virtual function, say hi(). The base class is pretty much pure. Now I declared a pointer of the the base class, and created a derived class object with the pointer. I tried to call hi(), but Visual C++ gave me some funny errors:

    d:\cryptography\crypter\crypter\crypter.cpp(149) : error C2248: 'BaseClass::Hi' : cannot access private member declared in class 'BaseClass'
    d:\cryptography\crypter\crypter\crypter.h(45) : see declaration of 'BaseClass::Hi'
    d:\cryptography\crypter\crypter\crypter.h(41) : see declaration of 'BaseClass

    can someone please help me?'

  2. #2
    Kernel hacker
    Join Date
    Jul 2007
    Farncombe, Surrey, England
    Hi() needs to be public.

    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  3. #3
    Registered User
    Join Date
    Sep 2007
    OMG thankyou! I was so dumb. Anyway, I get a new error: d:\cryptography\crypter\crypter\power.h(8) : error C2143: syntax error : missing ';' before 'using'

    and this is the bit where it points to.
    #ifndef POWER_H
    #define POWER_H
    #include <iostream>
    #include <string>
    #include "Crypter.h"
    using std::cout;    // here it is
    using std::cin;
    using std::endl;
    using std::string;
    typedef unsigned short int USINT;

  4. #4
    C++ Witch laserlight's Avatar
    Join Date
    Oct 2003
    The problem is probably in Crypter.h, perhaps it is a missing semi-colon for a class declaration.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  5. #5
    Registered User
    Join Date
    Sep 2007
    thanks alot guys, i did forget a semi-colon after a class declaration

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