### Define examples install path

Source: https://doc.qt.io/archives/qt-5.15/qtgui-qdocconf.html

Specifies the directory where examples will be installed relative to the parent examples directory.

```qdocconf
examplesinstallpath     = gui
```

--------------------------------

### Configure project file for Quick Items example

Source: https://doc.qt.io/archives/qt-5.15/qtquick3d-quickitems-quickitems-pro.html

Defines the project dependencies, installation path, and source files for the Quick Items example.

```qmake
QT += quick quick3d

target.path = $$[QT_INSTALL_EXAMPLES]/quick3d/quickitems

INSTALLS += target

SOURCES += \
    main.cpp

RESOURCES += \
    qml.qrc

OTHER_FILES += \
    doc/src/*.*
```

--------------------------------

### Specify example install path

Source: https://doc.qt.io/archives/qt-5.15/12-0-qdoc-commands-miscellaneous.html

Override the default installation path for an example by using the \meta command with the installpath attribute.

```qdoc
/ *!
    \example helloworld
    \title Hello World Example
    \meta {installpath} {tutorials}
* /
```

--------------------------------

### Main entry point for the Waterpump example

Source: https://doc.qt.io/archives/qt-5.15/qtopcua-waterpump-waterpump-qml-main-cpp.html

Initializes the application, locates and starts the simulation server process, and loads the main QML file.

```cpp
/****************************************************************************
**
** Copyright (C) 2018 basysKom GmbH, opensource@basyskom.com
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the QtOpcUa module.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**
** $QT_END_LICENSE$
**
****************************************************************************/


#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QFile>
#include <QDebug>
#include <QProcess>

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);

    QString serverExePath;
#ifdef Q_OS_WIN
    #ifdef QT_DEBUG
        serverExePath = app.applicationDirPath().append("/../../simulationserver/debug/simulationserver.exe");
    #else
        serverExePath = app.applicationDirPath().append("/../../simulationserver/release/simulationserver.exe");
    #endif
#elif defined(Q_OS_MACOS)
    serverExePath = app.applicationDirPath().append("/../../../../simulationserver/simulationserver.app/Contents/MacOS/simulationserver");
#else
    serverExePath = app.applicationDirPath().append("/../simulationserver/simulationserver");
#endif

    if (!QFile::exists(serverExePath)) {
        qWarning() << "Could not find server executable:" << serverExePath;
        return EXIT_FAILURE;
    }

    QProcess serverProcess;

    serverProcess.start(serverExePath);
    if (!serverProcess.waitForStarted()) {
        qWarning() << "Could not start server:" << serverProcess.errorString();
        return EXIT_FAILURE;
    }

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
        return EXIT_FAILURE;

    const int exitCode = QCoreApplication::exec();
    if (serverProcess.state() == QProcess::Running) {
#ifndef Q_OS_WIN
        serverProcess.terminate();
#else
        serverProcess.kill();
#endif
        serverProcess.waitForFinished();
    }
    return exitCode;
}
```

--------------------------------

### Configure Example Directories

Source: https://doc.qt.io/archives/qt-5.15/qtgui-qdocconf.html

Adds directories containing example source code for documentation.

```text
exampledirs += ../../../examples/gui \
               snippets
```

--------------------------------

### Documenting an example with \example

Source: https://doc.qt.io/archives/qt-5.15/13-qdoc-commands-topics.html

Defines an example path relative to the exampledirs configuration variable.

```qdoc
/ *!
    \example widgets/imageviewer
    \title ImageViewer Example
    \subtitle

    The example shows how to combine QLabel and QScrollArea
    to display an image.

    ...
* /
```

--------------------------------

### Define example directories and files

Source: https://doc.qt.io/archives/qt-5.15/22-qdoc-configuration-generalvariables.html

Sets the search paths for example source files and explicitly lists specific example files.

```qdoc
exampledirs = $QTDIR/doc/src \
              $QTDIR/examples \
              $QTDIR \
              $QTDIR/qmake/examples

examples    = $QTDIR/examples/widgets/analogclock/analogclock.cpp
```

--------------------------------

### Build and install Qt

Source: https://doc.qt.io/archives/qt-5.15/android-building.html

Compile the source code using make and install the resulting binaries.

```bash
make -j$(nproc)
```

```bash
make install
```

--------------------------------

### Install Qt

Source: https://doc.qt.io/archives/qt-5.15/integrity-building-qt-for-imx6quad-board.html

Install the built binaries if a custom prefix was not specified during configuration.

```bash
cd <Qt installation directory>
make install
```

--------------------------------

### Build and Install Qt

Source: https://doc.qt.io/archives/qt-5.15/android-building.html

Compiles the configured source code and installs the resulting binaries.

```batch
mingw32-make.exe -j<N>
```

```batch
mingw32-make.exe install
```

--------------------------------

### Build and Install Qt 5

Source: https://doc.qt.io/archives/qt-5.15/vxworks.html

Standard commands to compile and install the Qt 5 framework.

```bash
make -j<N>
make install
```

--------------------------------

### start()

Source: https://doc.qt.io/archives/qt-5.15/qbluetoothdevicediscoveryagent.html

Starts the Bluetooth device discovery process using default methods.

```APIDOC
## void start()

### Description
Starts the Bluetooth device discovery process using the default discovery methods.
```

--------------------------------

### bool QHelpEngineCore::setupData()

Source: https://doc.qt.io/archives/qt-5.15/qhelpenginecore.html

Initializes the help engine by processing the collection file.

```APIDOC
## bool QHelpEngineCore::setupData()

### Description
Sets up the help engine by processing the information found in the collection file and returns true if successful; otherwise returns false.
```

--------------------------------

### Set example directories

Source: https://doc.qt.io/archives/qt-5.15/qdoc-minimum-qdocconf.html

Defines the directory containing example source code files.

```qdocconf
exampledirs = .
```

--------------------------------

### start

Source: https://doc.qt.io/archives/qt-5.15/qknxnetipserverdiscoveryagent.html

Starts the server discovery process using various configuration options.

```APIDOC
## void start(QKnxNetIpServerDiscoveryAgent::InterfaceTypes types)

### Description
Starts the server discovery agent using the specified network interface types.

### Parameters
- **types** (QKnxNetIpServerDiscoveryAgent::InterfaceTypes) - The list of interface types to use for discovery.
```

--------------------------------

### Initialize the Application

Source: https://doc.qt.io/archives/qt-5.15/qtcore-ipc-sharedmemory-example.html

The main entry point creates the QApplication and displays the Dialog instance.

```cpp
int main(int argc, char *argv[])
{
    QApplication application(argc, argv);
    Dialog dialog;
    dialog.show();
    return application.exec();
}
```

--------------------------------

### Start Data Generation

Source: https://doc.qt.io/archives/qt-5.15/qtdatavisualization-itemmodel-example.html

Trigger the generator's start method after application setup.

```cpp
generator.start();
```

--------------------------------

### Query specific installation path

Source: https://doc.qt.io/archives/qt-5.15/qmake-environment-reference.html

Example of querying the installation prefix for the current qmake version.

```bash
qmake -query "QT_INSTALL_PREFIX"
```

--------------------------------

### Main entry point for MQTT Subscriptions example

Source: https://doc.qt.io/archives/qt-5.15/qtmqtt-subscriptions-main-cpp.html

Initializes the QApplication and displays the MainWindow for the MQTT Subscriptions application.

```cpp
/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**
** $QT_END_LICENSE$
**
****************************************************************************/


#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}
```

--------------------------------

### Linker error example

Source: https://doc.qt.io/archives/qt-5.15/windows-issues.html

Example of a linker error caused by installing Qt in a directory path containing spaces.

```text
c:\program.obj not found
```

--------------------------------

### QUICK_TEST_MAIN_WITH_SETUP(name, QuickTestSetupClass)

Source: https://doc.qt.io/archives/qt-5.15/qquicktest.html

Macro to define the entry point for a Qt Quick Test application with custom setup logic.

```APIDOC
## QUICK_TEST_MAIN_WITH_SETUP(name, QuickTestSetupClass)

### Description
Sets up the entry point for a Qt Quick Test application, allowing for additional setup code to execute before running the QML test via a QObject-derived class.

### Parameters
- **name** (identifier) - Required - Unique identifier for the test suite.
- **QuickTestSetupClass** (class) - Required - A pointer to a QObject-derived class containing setup logic.
```

--------------------------------

### Define idle state transitions

Source: https://doc.qt.io/archives/qt-5.15/qtscxml-sudoku-example.html

The idle state handles start and setup events, where setup initializes the game state and triggers a restart.

```xml
        <state id="idle">
            <transition event="start" target="playing"/>
            <transition event="setup" target="unsolved">
                <assign location="initState" expr="_event.data.initState"/>
                <raise event="restart"/>
            </transition>
            <state id="unsolved"/>
            <state id="solved"/>
        </state>
```

--------------------------------

### QLinearGradient::start

Source: https://doc.qt.io/archives/qt-5.15/qlineargradient.html

Methods to get and set the start point of the linear gradient.

```APIDOC
## QPointF start() const
## void setStart(const QPointF &start)
## void setStart(qreal x, qreal y)

### Description
Returns or sets the start point of the linear gradient in logical coordinates.
```

--------------------------------

### Initialize Application Main Entry Point

Source: https://doc.qt.io/archives/qt-5.15/qtscxml-sudoku-example.html

Sets up the QApplication, initializes the Sudoku state machine, and displays the main window.

```cpp
#include "mainwindow.h"
#include "sudoku.h"

#include <QApplication>

int main(int argc, char **argv)
{
    QApplication app(argc, argv);

    Sudoku machine;
    MainWindow mainWindow(&machine);

    machine.start();
    mainWindow.show();
    return app.exec();
}
```

--------------------------------

### Initialize and start audio playback

Source: https://doc.qt.io/archives/qt-5.15/qaudiooutput.html

Configures the audio format and device, then starts playback from a QFile.

```cpp
QFile sourceFile;   // class member.
QAudioOutput* audio; // class member.
{
    sourceFile.setFileName("/tmp/test.raw");
    sourceFile.open(QIODevice::ReadOnly);

    QAudioFormat format;
    // Set up the format, eg.
    format.setSampleRate(8000);
    format.setChannelCount(1);
    format.setSampleSize(8);
    format.setCodec("audio/pcm");
    format.setByteOrder(QAudioFormat::LittleEndian);
    format.setSampleType(QAudioFormat::UnSignedInt);

    QAudioDeviceInfo info(QAudioDeviceInfo::defaultOutputDevice());
    if (!info.isFormatSupported(format)) {
        qWarning() << "Raw audio format not supported by backend, cannot play audio.";
        return;
    }

    audio = new QAudioOutput(format, this);
    connect(audio, SIGNAL(stateChanged(QAudio::State)), this, SLOT(handleStateChanged(QAudio::State)));
    audio->start(&sourceFile);
}
```

--------------------------------

### Initialize Application and Window

Source: https://doc.qt.io/archives/qt-5.15/qtgui-openglwindow-example.html

Set up the QGuiApplication and configure the surface format for the OpenGL window.

```cpp
int main(int argc, char **argv)
{
    QGuiApplication app(argc, argv);

    QSurfaceFormat format;
    format.setSamples(16);

    TriangleWindow window;
    window.setFormat(format);
    window.resize(640, 480);
    window.show();

    window.setAnimating(true);

    return app.exec();
}
```

--------------------------------

### Start the client application

Source: https://doc.qt.io/archives/qt-5.15/qtvirtualkeyboard-deployment-guide.html

Command to launch the Line Edits example as a Wayland client.

```bash
./lineedits -platform wayland
```

--------------------------------

### Setup Script Engine and Translator

Source: https://doc.qt.io/archives/qt-5.15/qtscript-script-helloscript-example.html

Configures the QScriptEngine and installs translation functions for internationalization.

```cpp
    QApplication app(argc, argv);

    QScriptEngine engine;

    QTranslator translator;
    translator.load("helloscript_la");
    app.installTranslator(&translator);
    engine.installTranslatorFunctions();
```

--------------------------------

### Implement main application entry point

Source: https://doc.qt.io/archives/qt-5.15/remoteobjects-example-static-source.html

Initialize the node, acquire the replica, and pass it to the client object.

```cpp
#include <QCoreApplication>
#include "client.h"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QSharedPointer<SimpleSwitchReplica> ptr; // shared pointer to hold source replica

    QRemoteObjectNode repNode; // create remote object node
    repNode.connectToNode(QUrl(QStringLiteral("local:switch"))); // connect with remote host node

    ptr.reset(repNode.acquire<SimpleSwitchReplica>()); // acquire replica of source from host node

    Client rswitch(ptr); // create client switch object and pass reference of replica to it

    return a.exec();
}
```

--------------------------------

### Setup UI

Source: https://doc.qt.io/archives/qt-5.15/qtwidgets-tutorials-notepad-example.html

Initializes the user interface components.

```cpp
    ui->setupUi(this);
```

--------------------------------

### Run compliance tests in fuzzingclient mode

Source: https://doc.qt.io/archives/qt-5.15/qtwebsockets-testing.html

Build the echoserver example and start the Autobahn fuzzingclient.

```bash
cd your_build_dir/examples/websockets/echoserver
qmake your_src_dir/examples/websockets/echoserver/echoserver.pro
make

./echoserver -p 9001
```

```bash
cd ~
wstest -m fuzzingclient
```

--------------------------------

### Using \brief for a non-boolean property

Source: https://doc.qt.io/archives/qt-5.15/11-qdoc-commands-specialcontent.html

Example of using \brief for a property, which must start with 'The'.

```qdoc
/ *!
    \property QWidget::geometry
    \brief The geometry of the widget relative to its parent and
    excluding the window frame.

    When changing the geometry, the widget, if visible,
    receives a move event (moveEvent()) and/or a resize
    event (resizeEvent()) immediately.

    ...

   \sa frameGeometry(), rect(), ...
* /
```

--------------------------------

### Main Application Entry Point

Source: https://doc.qt.io/archives/qt-5.15/qtwidgets-draganddrop-dropsite-example.html

Initializes the QApplication and displays the DropSiteWindow.

```cpp
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    DropSiteWindow window;
    window.show();
    return app.exec();
}
```

--------------------------------

### QOpcUaGdsClient Usage

Source: https://doc.qt.io/archives/qt-5.15/qopcuagdsclient.html

Example demonstrating how to initialize a GDS client, handle authentication, and start the registration process.

```APIDOC
## QOpcUaGdsClient Usage

### Description
This example shows how to configure a QOpcUaGdsClient instance, provide authentication credentials via the authenticationRequired signal, and initiate the registration process.

### Code Example
```cpp
QOpcUaGdsClient c;

// In case the credentials are needed
QObject::connect(&c, &QOpcUaGdsClient::authenticationRequired, [&](QOpcUaAuthenticationInformation &authInfo) {
        authInfo.setUsernameAuthentication("root", "secret");
 });

// Await success
QObject::connect(&c, &QOpcUaGdsClient::applicationRegistered, [&]() {
    qDebug() << "Application" << c.applicationId() << "registered";
});

c.setBackend(...);
c.setEndpoint(...);
c.setApplicationIdentity(...);
c.setPkiConfiguration(...);
c.setApplicationRecord(...);
c.setCertificateSigningRequestPresets(...);
c.start();
```
```

--------------------------------

### Using \brief for a boolean property

Source: https://doc.qt.io/archives/qt-5.15/11-qdoc-commands-specialcontent.html

Example of using \brief for a boolean property, which must start with 'Whether'.

```qdoc
/ *!
    \property QWidget::isActiveWindow
    \brief Whether this widget's window is the active window.

    The active window is the window that contains the widget that
    has keyboard focus.

    When popup windows are visible, this property is \c true
    for both the active window \e and the popup.

    \sa activateWindow(), QApplication::activeWindow()
* /
```

--------------------------------

### Main Function Setup

Source: https://doc.qt.io/archives/qt-5.15/qtwebengine-webenginewidgets-printme-example.html

Initializes the QWebEngineView and connects keyboard shortcuts to the PrintHandler for print and print preview functionality.

```cpp
    QWebEngineView view;
    view.setUrl(QUrl(QStringLiteral("qrc:/index.html")));
    view.resize(1024, 750);
    view.show();

    PrintHandler handler;
    handler.setPage(view.page());

    auto printPreviewShortCut = new QShortcut(QKeySequence(Qt::CTRL + Qt::Key_P), &view);
    auto printShortCut = new QShortcut(QKeySequence(Qt::CTRL + Qt::SHIFT + Qt::Key_P), &view);

    QObject::connect(printPreviewShortCut, &QShortcut::activated, &handler, &PrintHandler::printPreview);
    QObject::connect(printShortCut, &QShortcut::activated, &handler, &PrintHandler::print);
```

--------------------------------

### Prepare variables for status reporting

Source: https://doc.qt.io/archives/qt-5.15/qstring.html

Example setup for using QStringView with arg() to construct progress status strings.

```cpp
int i;                // current file's number
int total;            // number of files to process
QStringView fileName; // current file's name
```

--------------------------------

### Define a Qt Quick Test Entry Point with Setup

Source: https://doc.qt.io/archives/qt-5.15/qquicktest.html

Use QUICK_TEST_MAIN_WITH_SETUP to execute custom setup code, such as configuring the QQmlEngine, before running QML tests.

```cpp
// tst_mytest.cpp
#include <QtQuickTest>
#include <QQmlEngine>
#include <QQmlContext>

class Setup : public QObject
{
    Q_OBJECT

public:
    Setup() {}

public slots:
    void qmlEngineAvailable(QQmlEngine *engine)
    {
        engine->rootContext()->setContextProperty("myContextProperty", QVariant(true));
    }
};

QUICK_TEST_MAIN_WITH_SETUP(mytest, Setup)

#include "tst_mytest.moc"
```

--------------------------------

### Configure project file for Principled Material

Source: https://doc.qt.io/archives/qt-5.15/qtquick3d-principledmaterial-principledmaterial-pro.html

Defines the project modules, installation path, and source files required for the example.

```qmake
QT += quick quick3d

target.path = $$[QT_INSTALL_EXAMPLES]/quick3d/principledmaterial
INSTALLS += target

SOURCES += \
    main.cpp

RESOURCES += \
    qml.qrc \
    materials.qrc

OTHER_FILES += \
    doc/src/*.*
```

--------------------------------

### Initialize QSettings with Organization and Application

Source: https://doc.qt.io/archives/qt-5.15/qsettings.html

Demonstrates the equivalence between a single-line constructor and setting global application metadata.

```cpp
QSettings settings("Moose Soft", "Facturo-Pro");
```

```cpp
QCoreApplication::setOrganizationName("Moose Soft");
QCoreApplication::setApplicationName("Facturo-Pro");
QSettings settings;
```

--------------------------------

### Complete minimal Q3DSurface example

Source: https://doc.qt.io/archives/qt-5.15/q3dsurface.html

A full implementation showing the setup, data population, and display of a 3D surface graph.

```cpp
#include <QtDataVisualization>

using namespace QtDataVisualization;

int main(int argc, char **argv)
{
    QGuiApplication app(argc, argv);

    Q3DSurface surface;
    surface.setFlags(surface.flags() ^ Qt::FramelessWindowHint);
    QSurfaceDataArray *data = new QSurfaceDataArray;
    QSurfaceDataRow *dataRow1 = new QSurfaceDataRow;
    QSurfaceDataRow *dataRow2 = new QSurfaceDataRow;

    *dataRow1 << QVector3D(0.0f, 0.1f, 0.5f) << QVector3D(1.0f, 0.5f, 0.5f);
    *dataRow2 << QVector3D(0.0f, 1.8f, 1.0f) << QVector3D(1.0f, 1.2f, 1.0f);
    *data << dataRow1 << dataRow2;

    QSurface3DSeries *series = new QSurface3DSeries;
    series->dataProxy()->resetArray(data);
    surface.addSeries(series);
    surface.show();

    return app.exec();
}
```

--------------------------------

### Configure Custom Materials project file

Source: https://doc.qt.io/archives/qt-5.15/qtquick3d-custommaterial-custommaterial-pro.html

Defines the project modules, installation path, and source files for the Custom Materials example.

```qmake
QT += quick quick3d

target.path = $$[QT_INSTALL_EXAMPLES]/quick3d/custommaterial
INSTALLS += target

SOURCES += \
    main.cpp

RESOURCES += \
    qml.qrc \
    materials.qrc

OTHER_FILES += \
    doc/src/*.*
```

--------------------------------

### Initialize Application and Parse Arguments

Source: https://doc.qt.io/archives/qt-5.15/qtwebengine-webenginewidgets-html2pdf-example.html

Sets up the application metadata and command line parser to handle input URL and output file path arguments. Requires a QApplication instance for Qt WebEngine functionality.

```cpp
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QCoreApplication::setOrganizationName("QtExamples");
    QCoreApplication::setApplicationName("html2pdf");
    QCoreApplication::setApplicationVersion(QT_VERSION_STR);

    QCommandLineParser parser;
    parser.setApplicationDescription(
        QCoreApplication::translate("main", "Converts the web page INPUT into the PDF file OUTPUT."));
    parser.addHelpOption();
    parser.addVersionOption();
    parser.addPositionalArgument(
        QCoreApplication::translate("main", "INPUT"),
        QCoreApplication::translate("main", "Input URL for PDF conversion."));
    parser.addPositionalArgument(
        QCoreApplication::translate("main", "OUTPUT"),
        QCoreApplication::translate("main", "Output file name for PDF conversion."));

    parser.process(QCoreApplication::arguments());

    const QStringList requiredArguments = parser.positionalArguments();
    if (requiredArguments.size() != 2)
        parser.showHelp(1);

    Html2PdfConverter converter(requiredArguments.at(0), requiredArguments.at(1));
    return converter.run();
}
```

--------------------------------

### Configure MQTT Subscriptions Project File

Source: https://doc.qt.io/archives/qt-5.15/qtmqtt-subscriptions-subscriptions-pro.html

Defines the necessary modules, source files, and installation paths for the MQTT Subscriptions example.

```qmake
QT       += core gui network widgets mqtt

TARGET = mqttsubscriptions

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += main.cpp\
        mainwindow.cpp \
    subscriptionwindow.cpp

HEADERS  += mainwindow.h \
    subscriptionwindow.h
FORMS    += mainwindow.ui \
    subscriptionwindow.ui

target.path = $$[QT_INSTALL_EXAMPLES]/mqtt/subscriptions
INSTALLS += target
```

--------------------------------

### Initialize and Configure QRadioTuner

Source: https://doc.qt.io/archives/qt-5.15/qradiotuner.html

Demonstrates basic setup of a radio tuner, including signal connection, band verification, and starting playback.

```cpp
radio = new QRadioTuner;
connect(radio, SIGNAL(frequencyChanged(int)), this, SLOT(freqChanged(int)));
if (radio->isBandSupported(QRadioTuner::FM)) {
    radio->setBand(QRadioTuner::FM);
    radio->setFrequency(yourRadioStationFrequency);
    radio->setVolume(100);
    radio->start();
}
```

--------------------------------

### Build and install Qt documentation

Source: https://doc.qt.io/archives/qt-5.15/windows-building.html

Commands to compile and install the Qt reference documentation for use in Qt Assistant.

```bash
nmake docs
```

```bash
nmake install_docs
```

--------------------------------

### Start a Qt Application on VxWorks

Source: https://doc.qt.io/archives/qt-5.15/vxworks.html

Example commands to set the library path and launch a Qt 5 application using shared libraries.

```shell
putenv "LD_LIBRARY_PATH=/sd0a/lib"
cd "/sd0a"
rtpSp("<Qt5_app>", 200, 0x100000, 0, 0x01000000)
```

--------------------------------

### Main Application Entry Point

Source: https://doc.qt.io/archives/qt-5.15/qtwidgets-itemviews-addressbook-example.html

Initializes the QApplication and displays the MainWindow.

```cpp
int main(int argc, char *argv[])
{
#ifdef Q_OS_ANDROID
    QApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
#endif
    QApplication app(argc, argv);
    MainWindow mw;
    mw.show();
    return app.exec();
}
```

--------------------------------

### Create an OPC UA client using QOpcUaProvider

Source: https://doc.qt.io/archives/qt-5.15/qopcuaprovider.html

Demonstrates how to retrieve available backends and instantiate a client using the first available option.

```cpp
QOpcUaProvider provider;
QStringList available = provider.availableBackends();
if (!available.isEmpty()) {
    QOpcUaClient *client = provider.createClient(available[0]);
    if (client)
        qDebug() << "Client successfully created";
}
```

--------------------------------

### Configure project file for KNX Tunneling

Source: https://doc.qt.io/archives/qt-5.15/qtknx-feature-feature-pro.html

Defines the project structure, required modules, and installation path for the KNX Tunneling Features example.

```qmake
TEMPLATE = app
TARGET = feature
INCLUDEPATH += .

CONFIG += c++11
QT += knx widgets network core

FORMS += mainwindow.ui

HEADERS += deviceitem.h \
           mainwindow.h

SOURCES += deviceitem.cpp \
           main.cpp \
           mainwindow.cpp

target.path = $$[QT_INSTALL_EXAMPLES]/knx/feature
INSTALLS += target
```

--------------------------------

### Initialize a Qt Quick Application in C++

Source: https://doc.qt.io/archives/qt-5.15/qtdoc-tutorials-alarms-main-cpp.html

Sets up the QGuiApplication and loads the main QML file via QQmlApplicationEngine. Includes a connection to handle object creation failures.

```cpp
/****************************************************************************
**
** Copyright (C) 2018 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include <QGuiApplication>
#include <QQmlApplicationEngine>

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;
    const QUrl url("qrc:/alarms/main.qml");
    QObject::connect(&engine, &QQmlApplicationEngine::objectCreated, &app,
                     [url](QObject *obj, const QUrl &objUrl) {
                         if (!obj && url == objUrl)
                             QCoreApplication::exit(-1);
                     },
                     Qt::QueuedConnection);
    engine.load(url);

    return app.exec();
}
```

--------------------------------

### Configure Qt OPC UA Viewer project file

Source: https://doc.qt.io/archives/qt-5.15/qtopcua-opcuaviewer-opcuaviewer-pro.html

Defines the project modules, source files, headers, and installation path for the OPC UA Viewer example.

```qmake
QT += opcua widgets
CONFIG += c++11
DEPENDPATH += INCLUDEPATH

SOURCES += main.cpp \
    mainwindow.cpp \
    opcuamodel.cpp \
    treeitem.cpp \
    certificatedialog.cpp

#install
target.path = $$[QT_INSTALL_EXAMPLES]/opcua/opcuaviewer
INSTALLS += target

HEADERS += \
    mainwindow.h \
    opcuamodel.h \
    treeitem.h \
    certificatedialog.h

FORMS += \
    certificatedialog.ui \
    mainwindow.ui
```

--------------------------------

### Initialize WebEngine and Server in main.cpp

Source: https://doc.qt.io/archives/qt-5.15/qtwebengine-webengine-customdialogs-example.html

Sets up the application, initializes QtWebEngine, and configures a local proxy and TCP server for authentication simulation.

```cpp
int main(int argc, char *argv[])
{
    QCoreApplication::setOrganizationName("QtExamples");
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QtWebEngine::initialize();

    Application app(argc, argv);

    QQmlApplicationEngine engine;
    Server *server = new Server(&engine);

    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    QTimer::singleShot(0, server, &Server::run);

    QNetworkProxy proxy;
    proxy.setType(QNetworkProxy::HttpProxy);
    proxy.setHostName("localhost");
    proxy.setPort(5555);
    QNetworkProxy::setApplicationProxy(proxy);

    return app.exec();
}
```

--------------------------------

### Main Entry Point

Source: https://doc.qt.io/archives/qt-5.15/activeqt-activeqt-qutlook-example.html

Initializes the QApplication and displays the AddressView widget.

```cpp
#include "addressview.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    AddressView view;
    view.setWindowTitle(QObject::tr("Qt Example - Looking at Outlook"));
    view.show();

    return a.exec();
}
```

--------------------------------

### Parsing KNX Project Files

Source: https://doc.qt.io/archives/qt-5.15/qtknx-knxproj-main-cpp.html

This example uses QKnxGroupAddressInfos to parse a specified KNX project file and output details about its structure, including installations and group addresses.

```cpp
/******************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtKnx module.
**
** $QT_BEGIN_LICENSE:GPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 or (at your option) any later version
** approved by the KDE Free Qt Foundation. The licenses are as published by
** the Free Software Foundation and appearing in the file LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$*
**
******************************************************************************/


#include <QtCore/QCommandLineParser>
#include <QtCore/qdebug.h>
#include <QtCore/qvector.h>
#include <QtCore/qversionnumber.h>
#include <QtCore/qxmlstream.h>
#include <QtKnx/qknxgroupaddressinfos.h>

int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);
    QCoreApplication::setApplicationName("knxproj");

    QCommandLineParser cliParser;
    cliParser.setApplicationDescription("KNX Project file parser");
    cliParser.addHelpOption();
    QCommandLineOption verboseOption({"v","verbose"},
                                     QCoreApplication::translate(
                                         "main", "Show more details of the project file."));
    cliParser.addOption(verboseOption);
    QCommandLineOption projFilePathOption(QStringList() << "p" << "project",
              QCoreApplication::translate("main", "Path to the project file to parse."),
              QCoreApplication::translate("main", "path"));
    cliParser.addOption(projFilePathOption);
    cliParser.process(app);

    bool verbose = cliParser.isSet(verboseOption);

    if (!cliParser.isSet(projFilePathOption)) {
        qInfo() << "Error: Missing project file name" << Qt::endl;
        cliParser.showHelp(EXIT_FAILURE);
    }

    QKnxGroupAddressInfos infos(cliParser.value(projFilePathOption));
    infos.parse();

    qInfo().noquote() << QString::fromLatin1("Opening project file: %1")
                         .arg(infos.projectFile());
    QString status = infos.errorString().isEmpty() ? "No errors" : infos.errorString();
    qInfo().noquote() << QString::fromLatin1("Status parsing project: %1")
                         .arg(status);
    qInfo().noquote() << QString::fromLatin1("Project ids found: %1")
                         .arg(infos.projectIds().size());

    if (infos.status() != QKnxGroupAddressInfos::Status::NoError) {
        qInfo() << "ERROR:" <<  infos;
        return EXIT_FAILURE;
    }

    for (const auto &projId: infos.projectIds()) {
        auto installations = infos.installations(projId);
        qInfo()<< " # project"<<infos.projectName(projId);
        qInfo().noquote() << QString::fromLatin1("     found %1 installation(s)")
                             .arg(installations.size());
        for (const QString &installation: installations) {
            auto groupAddresses = infos.addressInfos(projId, installation);
            qInfo().noquote() << QString::fromLatin1("  - Installation \"%1\"")
                                 .arg(installation);
            qInfo().noquote() << QString::fromLatin1("     found %1 Group address(es)")
                       .arg(groupAddresses.size());
            for (const QKnxGroupAddressInfo &addInfo: groupAddresses) {
                if (!addInfo.isValid())
                    return EXIT_FAILURE;
                if (verbose)
                    qInfo().noquote() << QString::fromLatin1("      %1: %2")
                                         .arg(addInfo.name()).arg(addInfo.address().toString());
            }
            qInfo() << Qt::endl;
        }
    }

    return EXIT_SUCCESS;
};
```

--------------------------------

### Initialize the QQuickView in main

Source: https://doc.qt.io/archives/qt-5.15/qtquick-scenegraph-openglunderqml-example.html

Sets up the application and loads the main QML file.

```cpp
int main(int argc, char **argv)
{
    QGuiApplication app(argc, argv);

    QQuickView view;
    view.setResizeMode(QQuickView::SizeRootObjectToView);
    view.setSource(QUrl("qrc:///scenegraph/openglunderqml/main.qml"));
    view.show();

    return app.exec();
}
```

--------------------------------

### Append an install set to the installation list

Source: https://doc.qt.io/archives/qt-5.15/qmake-advanced-usage.html

Registers the defined install set with the project's INSTALLS variable.

```qmake
INSTALLS += documentation
```

--------------------------------

### start()

Source: https://doc.qt.io/archives/qt-5.15/qml-qtsensors-compass-members.html

Starts the sensor. Returns true if the sensor was successfully started, otherwise false.

```APIDOC
### Method
bool start()

### Description
Starts the sensor. This method is inherited from the Sensor base class.

### Returns
- **bool** - Returns true if the sensor was successfully started, otherwise false.
```

--------------------------------

### Using the obsolete QProcess::start method

Source: https://doc.qt.io/archives/qt-5.15/qprocess-obsolete.html

Demonstrates the usage of the obsolete start method which accepts a single command string. Note that arguments with spaces must be quoted.

```cpp
QProcess process;
process.start("del /s *.txt");
// same as process.start("del", QStringList() << "/s" << "*.txt");
...
```

```cpp
QProcess process;
process.start("dir \"My Documents\"");
```

```cpp
QProcess process;
process.start("dir \"Epic 12\"\"\" Singles\"");
```

--------------------------------

### Configure Installation Targets

Source: https://doc.qt.io/archives/qt-5.15/qmake-variable-reference.html

Defines the installation path for a build target and adds it to the installation list.

```qmake
target.path += $$[QT_INSTALL_PLUGINS]/imageformats
INSTALLS += target
```

--------------------------------

### Initialize the application and QML engine

Source: https://doc.qt.io/archives/qt-5.15/qtquickcontrols-chattutorial-example.html

Sets up the application object and loads the main QML file, including high DPI scaling support.

```cpp
int main(int argc, char *argv[])
{
    QGuiApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

    return app.exec();
}
```

--------------------------------

### start()

Source: https://doc.qt.io/archives/qt-5.15/qml-qtquick-animation.html

Starts the animation.

```APIDOC
## start()

### Description
Starts the animation. If the animation is already running, calling this method has no effect.
```

--------------------------------

### start()

Source: https://doc.qt.io/archives/qt-5.15/qmovie.html

Starts the movie playback.

```APIDOC
## void start()

### Description
Starts the movie. The movie enters the Running state and emits started() and stateChanged() signals.
```

--------------------------------

### Main function implementation for Icons example

Source: https://doc.qt.io/archives/qt-5.15/qtwidgets-widgets-icons-example.html

Initializes the application, configures command-line options for High DPI support, and sets up the main window geometry.

```cpp
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QCoreApplication::setApplicationName(MainWindow::tr("Icons"));
    QCoreApplication::setApplicationVersion(QT_VERSION_STR);
    QCommandLineParser commandLineParser;
    commandLineParser.setSingleDashWordOptionMode(QCommandLineParser::ParseAsLongOptions);
    commandLineParser.addHelpOption();
    commandLineParser.addVersionOption();
    QCommandLineOption noHighDpiPixmapOption("no-highdpi-pixmaps",
                                             "Disable High DPI image loading (Qt::AA_UseHighDpiPixmaps)");
    commandLineParser.addOption(noHighDpiPixmapOption);
        commandLineParser.addPositionalArgument(MainWindow::tr("[file]"), MainWindow::tr("Icon file(s) to open."));
    commandLineParser.process(QCoreApplication::arguments());

    if (!commandLineParser.isSet(noHighDpiPixmapOption))
        QCoreApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);

    MainWindow mainWin;
    if (!commandLineParser.positionalArguments().isEmpty())
        mainWin.loadImages(commandLineParser.positionalArguments());

    const QRect availableGeometry = mainWin.screen()->availableGeometry();
    mainWin.resize(availableGeometry.width() / 2, availableGeometry.height() * 2 / 3);
    mainWin.move((availableGeometry.width() - mainWin.width()) / 2, (availableGeometry.height() - mainWin.height()) / 2);

    mainWin.show();
    return app.exec();
}
```

--------------------------------

### Build and install Qt binaries

Source: https://doc.qt.io/archives/qt-5.15/configure-options.html

Execute the build process and install the resulting binaries to the directory specified during configuration.

```bash
make
make install
```

--------------------------------

### start()

Source: https://doc.qt.io/archives/qt-5.15/qml-qtquick-animatedsprite.html

Starts the sprite animation.

```APIDOC
## start()

### Description
Starts the sprite animation. If the animation is already running, calling this method has no effect.
```

--------------------------------

### start()

Source: https://doc.qt.io/archives/qt-5.15/qml-qtmultimedia-camera.html

Starts the camera device.

```APIDOC
## start()

### Description
Starts the camera device.
```

--------------------------------

### Initialize QQmlApplicationEngine

Source: https://doc.qt.io/archives/qt-5.15/qqmlapplicationengine.html

Demonstrates the standard setup for a QML-based application using QQmlApplicationEngine.

```cpp
#include <QGuiApplication>
#include <QQmlApplicationEngine>

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    QQmlApplicationEngine engine("main.qml");
    return app.exec();
}
```

--------------------------------

### start()

Source: https://doc.qt.io/archives/qt-5.15/qml-qtmultimedia-radio.html

Starts the radio device.

```APIDOC
## start()

### Description
Starts the radio. If the radio is available, this will result in the state becoming ActiveState.
```

--------------------------------

### Initialize the Notepad Application

Source: https://doc.qt.io/archives/qt-5.15/qtwidgets-tutorials-notepad-example.html

The main entry point for the application, initializing the QApplication and displaying the main window.

```cpp
#include "notepad.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication EditorApp(argc, argv);
    Notepad Editor;
    Editor.show();

    return EditorApp.exec();
}
```

--------------------------------

### start

Source: https://doc.qt.io/archives/qt-5.15/qbluetoothservicediscoveryagent.html

Starts the service discovery process.

```APIDOC
## void start(QBluetoothServiceDiscoveryAgent::DiscoveryMode mode = MinimalDiscovery)

### Description
Starts the discovery process using the specified discovery mode.

### Parameters
- **mode** (DiscoveryMode) - The mode of discovery (MinimalDiscovery or FullDiscovery).
```

--------------------------------

### Main Application Entry Point

Source: https://doc.qt.io/archives/qt-5.15/qtwidgets-dialogs-trivialwizard-example.html

Instantiates the QWizard, adds the pages, and displays the wizard window.

```cpp
int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);

    QApplication app(argc, argv);

#ifndef QT_NO_TRANSLATION
    QString translatorFileName = QLatin1String("qtbase_");
    translatorFileName += QLocale::system().name();
    QTranslator *translator = new QTranslator(&app);
    if (translator->load(translatorFileName, QLibraryInfo::location(QLibraryInfo::TranslationsPath)))
        app.installTranslator(translator);
#endif

    QWizard wizard;
    wizard.addPage(createIntroPage());
    wizard.addPage(createRegistrationPage());
    wizard.addPage(createConclusionPage());

    wizard.setWindowTitle("Trivial Wizard");
    wizard.show();

    return app.exec();
}
```

--------------------------------

### Initialize and run the MQTT client application

Source: https://doc.qt.io/archives/qt-5.15/qtmqtt-simpleclient-main-cpp.html

The main entry point for the application, setting up the QApplication and displaying the MainWindow.

```cpp
/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/


#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}
```

--------------------------------

### start

Source: https://doc.qt.io/archives/qt-5.15/qaudiooutput.html

Starts the audio output process.

```APIDOC
## void start(QIODevice *device)
## QIODevice *start()

### Description
Starts sending audio data to the output device. If a device is provided, it reads from it; otherwise, it returns a QIODevice that the user can write data to.
```