文字列ベースとファンクターベースの接続の違い

    auto slider = new QSlider(this);
    auto doubleSpinBox = new QDoubleSpinBox(this);

    // OK: The compiler can convert an int into a double
    connect(slider, &QSlider::valueChanged,
            doubleSpinBox, &QDoubleSpinBox::setValue);

    // ERROR: The string table doesn't contain conversion information
    connect(slider, SIGNAL(valueChanged(int)),
            doubleSpinBox, SLOT(setValue(double)));

    auto audioInput = new QAudioInput(QAudioFormat(), this);
    auto widget = new QWidget(this);

    // OK
    connect(audioInput, SIGNAL(stateChanged(QAudio::State)),
            widget, SLOT(show()));

    // ERROR: The strings "State" and "QAudio::State" don't match
    using namespace QAudio;
    connect(audioInput, SIGNAL(stateChanged(State)),
            widget, SLOT(show()));

    // ...

class TextSender : public QWidget {
    Q_OBJECT

    QLineEdit *lineEdit;
    QPushButton *button;

signals:
    void textCompleted(const QString& text) const;

public:
    TextSender(QWidget *parent = nullptr);
};

TextSender::TextSender(QWidget *parent) : QWidget(parent) {
    lineEdit = new QLineEdit(this);
    button = new QPushButton("Send", this);

    connect(button, &QPushButton::clicked, [=] {
        emit textCompleted(lineEdit->text());
    });

    // ...
}

Rectangle {
    width: 100; height: 100

    signal qmlSignal(string sentMsg)
    function qmlSlot(receivedMsg) {
        console.log("QML received: " + receivedMsg)
    }

    MouseArea {
        anchors.fill: parent
        onClicked: qmlSignal("Hello from QML!")
    }
}

クラスCppGui :publicQWidget{Q_OBJECT    QPushButton*シグナル：voidcppSignal(constQVariant&sentMsg)const;public slots:voidcppSlot(constQString&receivedMsg)const{; public slots: void cppSlot(const&receivedMsg)const        qDebug() << "C++ received:" << receivedMsg;
    }public: CppGui(QWidget*parent =nullptr) ： QWidget(parent) { button= newQPushButton("Click Me!", this); connect(button, &::clicked, [=] { cppシグナルを出す。QPushButton::clicked, [=]{ cppSignal("Hello from C++!"); }); } };

    auto cppObj = new CppGui(this);
    auto quickWidget = new QQuickWidget(QUrl("QmlGui.qml"), this);
    auto qmlObj = quickWidget->rootObject();

    // Connect QML signal to C++ slot
    connect(qmlObj, SIGNAL(qmlSignal(QString)),
            cppObj, SLOT(cppSlot(QString)));

    // Connect C++ signal to QML slot
    connect(cppObj, SIGNAL(cppSignal(QVariant)),
            qmlObj, SLOT(qmlSlot(QVariant)));

public slots:voidprintNumber(intnumber= 42) { デフォルト引数を持つ次のようなスロットがあるとする。        qDebug() << "Lucky number" << number;
    }

DemoWidget::DemoWidget(QWidget*(parent) ： QWidget(parent) {// OK: printNumber() は、デフォルト値42で呼び出されます。    connect(qApp, SIGNAL(aboutToQuit()),
           this,SLOT(printNumber()));// ERROR：コンパイラーは互換性のある引数を要求します    connect(qApp, &QCoreApplication::aboutToQuit,
           this, &DemoWidget::printNumber); }

    auto slider = new QSlider(this);
    auto lcd = new QLCDNumber(this);

    // String-based syntax
    connect(slider, SIGNAL(valueChanged(int)),
            lcd, SLOT(display(int)));

    // Functor-based syntax
    connect(slider, &QSlider::valueChanged,
            lcd, qOverload<int>(&QLCDNumber::display));