qt QWidget *parent = 0

class GoToCellDialog : public QDialog, public Ui::GoToCellDialog
{
    Q_OBJECT

public:
    GoToCellDialog(QWidget *parent = 0);

private slots:
    void on_lineEdit_textChanged();
};

如代碼，QWidget *parent = 0 表示gotocell控件不是任何控件的子控件