LNK2001 can't resolve external symbol

JesusM

Hi, I am trying to make my QOpenGLWindow class a singleton so I can access from anywhere but I have an error that says :

glwindow.obj:-1: error: LNK2001: símbolo externo "private: static class glwindow * glwindow::instance" (?instance@glwindow@@0PEAV1@EA) sin resolver

The attribute that is throwing me that error is:

static glwindow *instance;

I have re-run QMake and also I have rebuilt all the proyect so I don't know what to do know.
I have another class that is working as a singleton and I have no problem with it.

This is my glwindow .h:

class glwindow : public QOpenGLWidget, protected QOpenGLFunctions_4_1_Core
{
    Q_OBJECT

public:

    static glwindow *getInstance();

    bool eventFilter(QObject *obj, QEvent *event) override;
    void window_refresh();

protected:

    void initializeGL() override;

    void resizeGL(int w, int h) override;

    void paintGL() override;

     ~glwindow() override;

private:

    glwindow(QWidget *parent = nullptr);

    static glwindow *instance;

    void printContextInformation();

};

Thanks

Christian Ehrlicher

@JesusM said in LNK2001 can't resolve external symbol:

static glwindow *instance;

Where do you have the definition for this? It's missing in glwindow.cpp I would guess.

JesusM

@Christian-Ehrlicher

Oh, I know what you mean. I had it initialized in the constructor but, as it is an static attribute I had to initialized it outside

glwindow::glwindow(QWidget *parent): QOpenGLWidget (parent)
{
    instance = nullptr;
}

So now I put it outside any function and It work's. My bad

glwindow * glwindow::instance = nullptr;

Thanks .