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Sharing Class functions

This is a discussion on Sharing Class functions within the C++ Programming forums, part of the General Programming Boards category; Hello there, it's been a while since I posted so it's nice to see you guys again! Straight to the ...

  1. #1
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    Sharing Class functions

    Hello there, it's been a while since I posted so it's nice to see you guys again!

    Straight to the point... I have a class which has a certain function, but I need that function to be used by another class. I made some research and the best solution might be using a "friend function". Is it the best way to do so? Can anyone shed some light on this topic for a better understanding? Thanks in advance.

    Code:
    class Playlist
    {
    public:
        Playlist();
    
    
        // "set" methods
        void setMusicList(const std::string& filename);
    
    
        // "get" methods
        std::vector<uint> getMusicList() const {return musicList;};
    
    
        // other
        void addSongToPlaylist(uint songID);
        void removeSongFromPlaylist(uint songID);
        void showPlaylist() const;  -> Function which needs to be used by a RadioStation (class) function
        void orderPlaylist();
        void writePlaylistToFile(const std::string& filename);
    
    
    private:
        std::vector<uint> musicList;
    
    
        // these methods can be private, the function orderPlaylist calls them
        void swapElementsInPlaylist();
        bool isOrdered() const;
    };
    
    
    class RadioStation
    {
    public:
        RadioStation(); // creates a radio station
    
    
        // "set" methods
        void setName(const std::string& n) {name = n;};
        void setTracksToBroadcast();
        void setTopTracks();
        void setUsers();
    
    
        // "get" methods
        std::string getName() const {return name;};
        Playlist getTTBroadcast() const {return tracksToBroadcast;};
        Playlist getTopTracks() const {return topTracks;};
        std::vector<User> getUsers() const {return radioUsers;};
    
    
        // other
        void addUser(User u); // adds a new listener to a previously created r station
        void createTopTenFile();
        void showTopTracks() const; //  show top ten tracks
        void createNewUser();
    
    
        // radio station menus
        void firstLaunch();
        void userAccount(const std::string& lineWithUserInfo);
        void userOptions(); -> Function which requires the "showPlaylist" function
        void login();
        void signup();
        void mainMenu();
    
    
    
    
    private:
        std::string name;
        Playlist tracksToBroadcast;
        Playlist topTracks;
        std::vector<User> radioUsers;
    
    
    };
    Last edited by Khabz; 05-25-2013 at 11:19 AM.

  2. #2
    ZuK
    ZuK is offline
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    I cannot see the problem. showPlaylist() is a public function of Playlist().
    RadioStation has two Playlist members tracksToBroadcast and topTracks

    so it is ok in RadioStation::userOptions() to call

    Code:
     topTracks.showPlaylist();
    or
    Code:
     tracksToBroadcast.showPlaylist();
    no friend needed

    Kurt
    phantomotap likes this.

  3. #3
    C++まいる!Cをこわせ! Elysia's Avatar
    Join Date
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    22,614
    Friends are for making private or protected data/functions available to specific outside functions/classes/structs. As your function is public, you don't need that.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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