Linker Error

This is a discussion on Linker Error within the C++ Programming forums, part of the General Programming Boards category; I have never had this problem before, and now i'm adding classes to my RPG, and all of the sethp,mp,etc ...

  1. #1
    C++ Beginner
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    Linker Error

    I have never had this problem before, and now i'm adding classes to my RPG, and all of the sethp,mp,etc says [Linker error] undefined reference to `User::sethp(int)' or something like that. What's wrong?
    I'm a beginner C++ programmer, but I have studied HTML and Java. So if you need to help me I should catch on fast =)

  2. #2
    Frequently Quite Prolix dwks's Avatar
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    You're calling User::sethp(int), and it isn't declared.
    dwk

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  3. #3
    Registered User hk_mp5kpdw's Avatar
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    You may have declared a method for your class but you lack the implementation for it, as an example:

    Code:
    class myclass
    {
    public:
        void bar(void);
    };
    
    int main()
    {
        myclass foo;
        foo.bar();
        return 0;
    }
    The class has a method called bar declared but there is no implementation for it anywhere. You would need to add the implementation:

    Code:
    void myclass::bar(void)
    {
        ...
    }
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
    -Christopher Hitchens

  4. #4
    C++ Beginner
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    yea just went back in some tuts and found that out. I learned inhertiance and some poly, and i didn't know something like that, dumb.
    I'm a beginner C++ programmer, but I have studied HTML and Java. So if you need to help me I should catch on fast =)

  5. #5
    C++ Beginner
    Join Date
    Jun 2005
    Posts
    39
    oh I get it now... I thought u didn't have to do that

    I thought u could just sethp();

    Code:
    class User 
    public:
    User();
    ~User();
    int gethp() { return hp }
    void sethp(int hp);
    private:
    int hp
    }
    doesn't work as an example?
    I'm a beginner C++ programmer, but I have studied HTML and Java. So if you need to help me I should catch on fast =)

  6. #6
    Registered User hk_mp5kpdw's Avatar
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    Code:
    class User
    {
    public:
    User();
    ~User();
    int gethp() { return hp; }
    void sethp(int hp);
    private:
    int hp;
    };
    Well, aside from the missing semicolons and bracket, that would need the implementation for the sethp method for it to work. You could either include the implementation as you've done with the gethp method (as a part of the class declaration) or you would need to define it elsewhere.
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
    -Christopher Hitchens

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