Question

I’m getting a linker error in xcode and I’m having a hard time understanding and finding the problem. This is the error I’m getting:

---

My Instrument class looks like this:

class Instrument {

private:

public:

    virtual float getSample(Note &note);
    Instrument(){}

};

And it’s implemented by my Synth class:

class Synth : public Instrument{

private:
    Volume volume;
public:
    Synth(){}
    void setVolume(float aVolume);
    virtual float getSample(Note &note);
};

And I’m using Instrument as a member in my Track class:

class Track {
public:
    bool muted;
    Instrument instrument;
Track(){
    this->muted = false;
}
};

Any ideas what is causing the problem? And I have one more question: If have a Track object, what is the best way to initialize it’s instrument member as a Synth? Would this work?

Track track;
track.instrument = Synth();

Answer 1

As Note in error says, you need to provide definition of virtual function which is missing I guess : Instrument::getSample(Note &note);

but I guess you need pure virtual function, make it:

class Instrument {
//...
public:
    virtual float getSample(Note &note) =0;
    Instrument(){}
};

if that’s not the case , post more code and check your code on different compiler , might be your compiler is buggy