QtWidgets: replace 0 with \nullptr in documentation

Replace 0 with \nullptr in the documentation.
As a drive-by also replace some 0 with nullptr in the corresponding
code.

Change-Id: I8d7e9c838da1399988a830669d58fc7f2f010696
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

examples/widgets/animation/sub-attaq/qanimationstate.cpp

@@ -118,7 +118,7 @@ void QAnimationState::setAnimation(QAbstractAnimation *animation)
 }
 
 /*!
-  Returns the animation handle by this animation state, or 0 if there is no animation.
+  Returns the animation handle by this animation state, or \nullptr if there is no animation.
 */
 QAbstractAnimation* QAnimationState::animation() const
 {

src/widgets/widgets/qabstractscrollarea.cpp

@@ -820,7 +820,7 @@ QWidget *QAbstractScrollArea::cornerWidget() const
 
     All widgets set here will be deleted by the scroll area when it is
     destroyed unless you separately reparent the widget after setting
-    some other corner widget (or 0).
+    some other corner widget (or \nullptr).
 
     Any \e newly set widget should have no current parent.
 

src/widgets/widgets/qbuttongroup.cpp

@@ -291,8 +291,8 @@ QList<QAbstractButton*> QButtonGroup::buttons() const
 }
 
 /*!
-    Returns the button group's checked button, or 0 if no buttons are
+    Returns the button group's checked button, or \nullptr if no
-    checked.
+    buttons are checked.
 
     \sa buttonClicked()
 */
@@ -305,8 +305,8 @@ QAbstractButton *QButtonGroup::checkedButton() const
 /*!
     \since 4.1
 
-    Returns the button with the specified \a id, or 0 if no such button
+    Returns the button with the specified \a id, or \nullptr if no
-    exists.
+    such button exists.
 */
 QAbstractButton *QButtonGroup::button(int id) const
 {

src/widgets/widgets/qcombobox.cpp

@@ -1888,8 +1888,8 @@ void QComboBox::setLineEdit(QLineEdit *edit)
 }
 
 /*!
-    Returns the line edit used to edit items in the combobox, or 0 if there
+    Returns the line edit used to edit items in the combobox, or
-    is no line edit.
+    \nullptr if there is no line edit.
 
     Only editable combo boxes have a line edit.
 */

src/widgets/widgets/qdialogbuttonbox.cpp

@@ -820,7 +820,7 @@ QDialogButtonBox::StandardButtons QDialogButtonBox::standardButtons() const
 
 /*!
     Returns the QPushButton corresponding to the standard button \a which,
-    or 0 if the standard button doesn't exist in this button box.
+    or \nullptr if the standard button doesn't exist in this button box.
 
     \sa standardButton(), standardButtons(), buttons()
 */

src/widgets/widgets/qdockwidget.cpp

@@ -1732,8 +1732,8 @@ void QDockWidget::setTitleBarWidget(QWidget *widget)
 
 /*!
     \since 4.3
-    Returns the custom title bar widget set on the QDockWidget, or 0 if no
+    Returns the custom title bar widget set on the QDockWidget, or
-    custom title bar has been set.
+    \nullptr if no custom title bar has been set.
 
     \sa setTitleBarWidget()
 */

src/widgets/widgets/qlineedit.cpp

@@ -586,7 +586,7 @@ void QLineEdit::setEchoMode(EchoMode mode)
 
 #ifndef QT_NO_VALIDATOR
 /*!
-    Returns a pointer to the current input validator, or 0 if no
+    Returns a pointer to the current input validator, or \nullptr if no
     validator has been set.
 
     \sa setValidator()

src/widgets/widgets/qmdiarea.cpp

@@ -1774,7 +1774,7 @@ QSize QMdiArea::minimumSizeHint() const
 }
 
 /*!
-    Returns a pointer to the current subwindow, or 0 if there is
+    Returns a pointer to the current subwindow, or \nullptr if there is
     no current subwindow.
 
     This function will return the same as activeSubWindow() if
@@ -1786,13 +1786,13 @@ QMdiSubWindow *QMdiArea::currentSubWindow() const
 {
     Q_D(const QMdiArea);
     if (d->childWindows.isEmpty())
-        return 0;
+        return nullptr;
 
     if (d->active)
         return d->active;
 
     if (d->isActivated && !window()->isMinimized())
-        return 0;
+        return nullptr;
 
     Q_ASSERT(d->indicesToActivatedChildren.count() > 0);
     int index = d->indicesToActivatedChildren.at(0);
@@ -1804,7 +1804,7 @@ QMdiSubWindow *QMdiArea::currentSubWindow() const
 
 /*!
     Returns a pointer to the current active subwindow. If no
-    window is currently active, 0 is returned.
+    window is currently active, \nullptr is returned.
 
     Subwindows are treated as top-level windows with respect to
     window state, i.e., if a widget outside the MDI area is the active
@@ -1821,7 +1821,7 @@ QMdiSubWindow *QMdiArea::activeSubWindow() const
 }
 
 /*!
-    Activates the subwindow \a window. If \a window is 0, any
+    Activates the subwindow \a window. If \a window is \nullptr, any
     current active window is deactivated.
 
     \sa activeSubWindow()
@@ -1830,7 +1830,7 @@ void QMdiArea::setActiveSubWindow(QMdiSubWindow *window)
 {
     Q_D(QMdiArea);
     if (!window) {
-        d->activateWindow(0);
+        d->activateWindow(nullptr);
         return;
     }
 

src/widgets/widgets/qmdisubwindow.cpp

@@ -2576,7 +2576,8 @@ void QMdiSubWindow::showSystemMenu()
 /*!
     \since 4.4
 
-    Returns the area containing this sub-window, or 0 if there is none.
+    Returns the area containing this sub-window, or \nullptr if there
+    is none.
 
     \sa QMdiArea::addSubWindow()
 */
@@ -2590,7 +2591,7 @@ QMdiArea *QMdiSubWindow::mdiArea() const
         }
         parent = parent->parentWidget();
     }
-    return 0;
+    return nullptr;
 }
 
 /*!

src/widgets/widgets/qmenu.cpp

@@ -2196,7 +2196,7 @@ void QMenu::setActiveAction(QAction *act)
 
 
 /*!
-    Returns the currently highlighted action, or 0 if no
+    Returns the currently highlighted action, or \nullptr if no
     action is currently highlighted.
 */
 QAction *QMenu::activeAction() const
@@ -2564,8 +2564,8 @@ void QMenu::popup(const QPoint &p, QAction *atAction)
     This is equivalent to \c{exec(pos())}.
 
     This returns the triggered QAction in either the popup menu or one
-    of its submenus, or 0 if no item was triggered (normally because
+    of its submenus, or \nullptr if no item was triggered (normally
-    the user pressed Esc).
+    because the user pressed Esc).
 
     In most situations you'll want to specify the position yourself,
     for example, the current mouse position:
@@ -2591,8 +2591,8 @@ QAction *QMenu::exec()
     coordinates into global coordinates, use QWidget::mapToGlobal().
 
     This returns the triggered QAction in either the popup menu or one
-    of its submenus, or 0 if no item was triggered (normally because
+    of its submenus, or \nullptr if no item was triggered (normally
-    the user pressed Esc).
+    because the user pressed Esc).
 
     Note that all signals are emitted as usual. If you connect a
     QAction to a slot and call the menu's exec(), you get the result
@@ -2628,11 +2628,11 @@ QAction *QMenu::exec(const QPoint &p, QAction *action)
     QPointer<QObject> guard = this;
     (void) eventLoop.exec();
     if (guard.isNull())
-        return 0;
+        return nullptr;
 
     action = d->syncAction;
-    d->syncAction = 0;
+    d->syncAction = nullptr;
-    d->eventLoop = 0;
+    d->eventLoop = nullptr;
     return action;
 }
 
@@ -2650,7 +2650,7 @@ QAction *QMenu::exec(const QPoint &p, QAction *action)
     QGraphicsView).
 
     The function returns the triggered QAction in either the popup
-    menu or one of its submenus, or 0 if no item was triggered
+    menu or one of its submenus, or \nullptr if no item was triggered
     (normally because the user pressed Esc).
 
     This is equivalent to:

src/widgets/widgets/qpushbutton.cpp

@@ -545,8 +545,8 @@ void QPushButton::setMenu(QMenu* menu)
 }
 
 /*!
-    Returns the button's associated popup menu or 0 if no popup menu
+    Returns the button's associated popup menu or \nullptr if no popup
-    has been set.
+    menu has been set.
 
     \sa setMenu()
 */

src/widgets/widgets/qscrollarea.cpp

@@ -217,7 +217,7 @@ void QScrollAreaPrivate::updateScrollBars()
 }
 
 /*!
-    Returns the scroll area's widget, or 0 if there is none.
+    Returns the scroll area's widget, or \nullptr if there is none.
 
     \sa setWidget()
 */

src/widgets/widgets/qstackedwidget.cpp

@@ -220,7 +220,7 @@ int QStackedWidget::currentIndex() const
 }
 
 /*!
-    Returns the current widget, or 0 if there are no child widgets.
+    Returns the current widget, or \nullptr if there are no child widgets.
 
     \sa currentIndex(), setCurrentWidget()
 */
@@ -260,8 +260,8 @@ int QStackedWidget::indexOf(QWidget *widget) const
 }
 
 /*!
-    Returns the widget at the given \a index, or 0 if there is no such
+    Returns the widget at the given \a index, or \nullptr if there is
-    widget.
+    no such widget.
 
     \sa currentWidget(), indexOf()
 */

src/widgets/widgets/qtabbar.cpp

@@ -2567,7 +2567,7 @@ void QTabBar::setChangeCurrentOnDrag(bool change)
 
     The tab bar will take ownership of the widget and so all widgets set here
     will be deleted by the tab bar when it is destroyed unless you separately
-    reparent the widget after setting some other widget (or 0).
+    reparent the widget after setting some other widget (or \nullptr).
 
     \sa tabsClosable()
   */
@@ -2597,14 +2597,14 @@ void QTabBar::setTabButton(int index, ButtonPosition position, QWidget *widget)
 }
 
 /*!
-    Returns the widget set a tab \a index and \a position or 0 if
+    Returns the widget set a tab \a index and \a position or \nullptr
-    one is not set.
+    if one is not set.
   */
 QWidget *QTabBar::tabButton(int index, ButtonPosition position) const
 {
     Q_D(const QTabBar);
     if (index < 0 || index >= d->tabList.count())
-        return 0;
+        return nullptr;
     if (position == LeftSide)
         return d->tabList.at(index).leftWidget;
     else

src/widgets/widgets/qtabwidget.cpp

@@ -579,7 +579,7 @@ void QTabWidget::setTabEnabled(int index, bool enable)
 
   All widgets set here will be deleted by the tab widget when it is
   destroyed unless you separately reparent the widget after setting
-  some other corner widget (or 0).
+  some other corner widget (or \nullptr).
 
   Note: Corner widgets are designed for \l North and \l South tab positions;
   other orientations are known to not work properly.
@@ -605,7 +605,7 @@ void QTabWidget::setCornerWidget(QWidget * widget, Qt::Corner corner)
 }
 
 /*!
-    Returns the widget shown in the \a corner of the tab widget or 0.
+    Returns the widget shown in the \a corner of the tab widget or \nullptr.
 */
 QWidget * QTabWidget::cornerWidget(Qt::Corner corner) const
 {
@@ -1146,8 +1146,8 @@ void QTabWidget::keyPressEvent(QKeyEvent *e)
 }
 
 /*!
-    Returns the tab page at index position \a index or 0 if the \a
+    Returns the tab page at index position \a index or \nullptr if the
-    index is out of range.
+    \a index is out of range.
 */
 QWidget *QTabWidget::widget(int index) const
 {

src/widgets/widgets/qtoolbox.cpp

@@ -504,7 +504,8 @@ int QToolBox::currentIndex() const
 }
 
 /*!
-    Returns a pointer to the current widget, or 0 if there is no such item.
+    Returns a pointer to the current widget, or \nullptr if there is
+    no such item.
 
     \sa currentIndex(), setCurrentWidget()
 */
@@ -512,7 +513,7 @@ int QToolBox::currentIndex() const
 QWidget * QToolBox::currentWidget() const
 {
     Q_D(const QToolBox);
-    return d->currentPage ? d->currentPage->widget : 0;
+    return d->currentPage ? d->currentPage->widget : nullptr;
 }
 
 /*!
@@ -530,15 +531,15 @@ void QToolBox::setCurrentWidget(QWidget *widget)
 }
 
 /*!
-    Returns the widget at position \a index, or 0 if there is no such
+    Returns the widget at position \a index, or \nullptr if there is
-    item.
+    no such item.
 */
 
 QWidget *QToolBox::widget(int index) const
 {
     Q_D(const QToolBox);
     if (index < 0 || index >= (int) d->pageList.size())
-        return 0;
+        return nullptr;
     return d->pageList.at(index).widget;
 }
 

src/widgets/widgets/qtoolbutton.cpp

@@ -669,7 +669,8 @@ void QToolButton::setMenu(QMenu* menu)
 }
 
 /*!
-    Returns the associated menu, or 0 if no menu has been defined.
+    Returns the associated menu, or \nullptr if no menu has been
+    defined.
 
     \sa setMenu()
 */
@@ -678,7 +679,7 @@ QMenu* QToolButton::menu() const
     Q_D(const QToolButton);
     if (d->menuAction)
         return d->menuAction->menu();
-    return 0;
+    return nullptr;
 }
 
 /*!