Question

I’m trying to create a menu in Qt following this example http://doc.qt.nokia.com/latest/mainwindows-menus.html

but I keep getting the error ‘menuBar’ not declared in this scope

 void Window::createMenus()
 {
     saveMenu = menuBar()->addMenu("&Save");


 }

In context:

 #include <QtGui>

 #include "borderlayout.h"
 #include "window.h"

 Window::Window()
 {
     QTextBrowser *centralWidget = new QTextBrowser;
     //***Change this to whatever widget(s) the drawing area is. QPainter or something?

     centralWidget->setPlainText(tr("DRAW HERE YAY"));

     BorderLayout *layout = new BorderLayout;
     layout->addWidget(centralWidget, BorderLayout::Center);
     layout->addWidget(createLabel("File ..."), BorderLayout::North);
     layout->addWidget(createLabel("Toolbar yo!"), BorderLayout::West);
     //layout->addWidget(createLabel("Status bar"), BorderLayout::South);
     //Maybe we could put in a status bar. For now let's not worry about it. It's not a requirement.
     setLayout(layout);
     createMenus();

     setWindowTitle(tr("Border Layout"));
 }

 QLabel *Window::createLabel(const QString &text)
 {
     QLabel *label = new QLabel(text);
     label->setFrameStyle(QFrame::Box | QFrame::Raised);
     return label;
 }

 void Window::createMenus()
 {
     saveMenu = menuBar()->addMenu("&Save");


 }

window.h

 #ifndef WINDOW_H
 #define WINDOW_H

 #include <QWidget>

 class QLabel;
 class QMenu;

 class Window : public QWidget
 {
     Q_OBJECT

 public:
     Window();

 private:
     void createMenus();

     QLabel *createLabel(const QString &text);
     QMenu *saveMenu();
 };

 #endif

window.cpp

 #include <QtGui>

 #include "borderlayout.h"
 #include "window.h"

 Window::Window()
 {
     QTextBrowser *centralWidget = new QTextBrowser;
     //***Change this to whatever widget(s) the drawing area is. QPainter or something?

     centralWidget->setPlainText(tr("DRAW HERE YAY"));

     BorderLayout *layout = new BorderLayout;
     layout->addWidget(centralWidget, BorderLayout::Center);
     layout->addWidget(createLabel("File ..."), BorderLayout::North);
     layout->addWidget(createLabel("Toolbar yo!"), BorderLayout::West);
     //layout->addWidget(createLabel("Status bar"), BorderLayout::South);
     //Maybe we could put in a status bar. For now let's not worry about it. It's not a requirement.
     setLayout(layout);
     createMenus();

     setWindowTitle(tr("Border Layout"));
 }

 QLabel *Window::createLabel(const QString &text)
 {
     QLabel *label = new QLabel(text);
     label->setFrameStyle(QFrame::Box | QFrame::Raised);
     return label;
 }

 void Window::createMenus()
 {
     saveMenu = menuBar()->addMenu("&Save");


 }

Answer 1

The menu bar is a feature of the QMainWindow class.

Because your Window class is being inherited directly from QWidget, it does not have the menuBar method, hence your error.

You need to subclass your Window class from QMainWindow rather than QWidget.