How is a constructor for a derived class supposed to be like in c++ when derived class has added data member

Question

I am new to c++. I have been trying to get past this error. I know when a class in derived, it inherits everything from the base class, but what if the derived class has other data members? How is the constructor suppose to be?

When I try putting only the new I try to pass parameters to the newly made class members in the constructor I get an error to say it doesn't match that of the base class. When I try using that of the base class and adding the new data members it tells me I am redefining. So I wonder whats left to do to get past this error below is my code.

This is the base class:

class movielibrarybase
{


public:
        movielibrarybase(string name, string dirname, string gen, int price);

        void setname(string name);
        string getname();

        void setdirector_name(string dirname);
        string getdirector_name();

        void setgenre(string gen);
        string getgenre();


        void setprice(int price);
        int getprice();

        void display();

        ~movielibrarybase();

    protected:
    string name;
    string director_name;
    string genre;
    int price;
};

And this is the derived class:

class songlibrary: public movielibrarybase
{
    public:
        songlibrary();


        void setartist_name(string name);
        string getartist_name();



        void setsong_position(string position);
        string getsong_position;

        ~songlibrary();


    protected:

    string artist_name;
    string song_postion;
};

I am getting the following errors:

songlibrary.cpp||In constructor 'songlibrary::songlibrary(std::string, std::string, std::string, int, std::string, std::string)':| songlibrary.cpp|6|error: no matching function for call to 'movielibrarybase::movielibrarybase()'| movielibrarybase.cpp|3|note: candidates are: movielibrarybase::movielibrarybase(std::string, std::string, std::string, int)| movielibrarybase.h|8|note: movielibrarybase::movielibrarybase(const movielibrarybase&)| songlibrary.cpp|34|error: no 'std::string songlibrary::getsong_position()' member function declared in class 'songlibrary'|

If your computer has a mouse, use it to copy the actual compiler messages and paste them to the question edit box. — n. 1.8e9-where's-my-share m.

ravi ravi · Accepted Answer · 2014-11-08T19:08:45

In your case it would be something like:-

songlibrary::songlibrary( string n, string director, string gen, 
                          int pri, string artist, string song )

                     : movielibrarybase( n, director, gen, pri ), 
                       artist_name( artist ), song_postion( song )

One thing to note here is sequence in member initializer list matters. First calls should be to base classes and then derived classes members should be initialized in the order in which they are declared in a class.

Also, class members are initialized in the order of their declaration in the class, the order in which they are listed in a member initialization list makes not a whit of difference

How is a constructor for a derived class supposed to be like in c++ when derived class has added data member

2 Answers