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Qt5 Tutorial Hello World - 2020





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Qt 5 Changes

According to qt-project.org, Qt Quick is now in the center of Qt.

For changes in Qt5, please visit
QtDoc 5 C++ API changes..




On This Tutorial

Since the documentation and manuals of Qt (including the ones from the Qt communities) are superb, I've been wondering if there is any need of additional tutorial.

However, Qt's been growing for quite a long time, and it become huge in terms of materials to master and hard to keep up with the pace. So, my excuse for this tutorial is "We (may) need Qt Express!"

Most of the materials of this tutorial is extremely simple but eventually covers lots of topics with core samples (I admit I've just started, and it's just beginning of a long Journey).

I believe, in that way, we can taste variety of features that Qt provides without giving up in despair.

Qt Express!

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Video recording - Producer and Consumer model using QSemaphore, for more info, please visit:

QSemaphores - Producer and Consumer.






Qt Version

We're using Qt 5.1 and QtCreator2.7.2 IDE:

QtCreater272.png


Hello World

In this tutorial, we will print out simple text "Hello World".

File->New File or Project...

NewProject.png

Applications->Qt Console Application->Choose...

ConsoleLocation.png

Let's see the main.cpp file that Creator made for us:

#include <QCoreApplication>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    
    return a.exec();
}

The QCoreApplication class provides an event loop for console Qt applications. This class is used by non-GUI applications to provide their event loop. For non-GUI application that uses Qt, there should be exactly one QCoreApplication object. For GUI applications, we will use QApplication.

When calling a.exec() the event loop is launched.

Let's compile this application. By clicking on the green arrow on the bottom left, Qt Creator will compile and execute it. And what happened ? The application seems to be launched and not responding. It is actually normal. The event loop is running and waiting for events such as mouse click, but we did not provide any event to be processed, so it will run indefinitely.

When we compile the project, behind the scene, our Qt app is compiled in the following steps:

  1. qmake parses the .pro file, and generates makefile.
  2. The program is build using make (jom on windows).

Let's print out "Hello World"i by modifying the source:

#include <QCoreApplication>
#include <QDebug>
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    
    qDebug() << "Hello World";

    return a.exec();
}

If we run the code again, it prints out "Hello World".







Qt 5 Tutorial

  1. Hello World
  2. Signals and Slots
  3. Q_OBJECT Macro
  4. MainWindow and Action
  5. MainWindow and ImageViewer using Designer A
  6. MainWindow and ImageViewer using Designer B
  7. Layouts
  8. Layouts without Designer
  9. Grid Layouts
  10. Splitter
  11. QDir
  12. QFile (Basic)
  13. Resource Files (.qrc)
  14. QComboBox
  15. QListWidget
  16. QTreeWidget
  17. QAction and Icon Resources
  18. QStatusBar
  19. QMessageBox
  20. QTimer
  21. QList
  22. QListIterator
  23. QMutableListIterator
  24. QLinkedList
  25. QMap
  26. QHash
  27. QStringList
  28. QTextStream
  29. QMimeType and QMimeDatabase
  30. QFile (Serialization I)
  31. QFile (Serialization II - Class)
  32. Tool Tips in HTML Style and with Resource Images
  33. QPainter
  34. QBrush and QRect
  35. QPainterPath and QPolygon
  36. QPen and Cap Style
  37. QBrush and QGradient
  38. QPainter and Transformations
  39. QGraphicsView and QGraphicsScene
  40. Customizing Items by inheriting QGraphicsItem
  41. QGraphicsView Animation
  42. FFmpeg Converter using QProcess
  43. QProgress Dialog - Modal and Modeless
  44. QVariant and QMetaType
  45. QtXML - Writing to a file
  46. QtXML - QtXML DOM Reading
  47. QThreads - Introduction
  48. QThreads - Creating Threads
  49. Creating QThreads using QtConcurrent
  50. QThreads - Priority
  51. QThreads - QMutex
  52. QThreads - GuiThread
  53. QtConcurrent QProgressDialog with QFutureWatcher
  54. QSemaphores - Producer and Consumer
  55. QThreads - wait()
  56. MVC - ModelView with QListView and QStringListModel
  57. MVC - ModelView with QTreeView and QDirModel
  58. MVC - ModelView with QTreeView and QFileSystemModel
  59. MVC - ModelView with QTableView and QItemDelegate
  60. QHttp - Downloading Files
  61. QNetworkAccessManager and QNetworkRequest - Downloading Files
  62. Qt's Network Download Example - Reconstructed
  63. QNetworkAccessManager - Downloading Files with UI and QProgressDialog
  64. QUdpSocket
  65. QTcpSocket
  66. QTcpSocket with Signals and Slots
  67. QTcpServer - Client and Server
  68. QTcpServer - Loopback Dialog
  69. QTcpServer - Client and Server using MultiThreading
  70. QTcpServer - Client and Server using QThreadPool
  71. Asynchronous QTcpServer - Client and Server using QThreadPool
  72. Qt Quick2 QML Animation - A
  73. Qt Quick2 QML Animation - B
  74. Short note on Ubuntu Install
  75. OpenGL with QT5
  76. Qt5 Webkit : Web Browser with QtCreator using QWebView Part A
  77. Qt5 Webkit : Web Browser with QtCreator using QWebView Part B
  78. Video Player with HTML5 QWebView and FFmpeg Converter
  79. Qt5 Add-in and Visual Studio 2012
  80. Qt5.3 Installation on Ubuntu 14.04
  81. Qt5.5 Installation on Ubuntu 14.04
  82. Short note on deploying to Windows







Ph.D. / Golden Gate Ave, San Francisco / Seoul National Univ / Carnegie Mellon / UC Berkeley / DevOps / Deep Learning / Visualization

YouTubeMy YouTube channel

Sponsor Open Source development activities and free contents for everyone.

Thank you.

- K Hong






Sponsor Open Source development activities and free contents for everyone.

Thank you.

- K Hong







Qt 5 Tutorial



Hello World

Signals and Slots

Q_OBJECT Macro

MainWindow and Action

MainWindow and ImageViewer using Designer A

MainWindow and ImageViewer using Designer B

Layouts

Layouts without Designer

Grid Layouts

Splitter

QDir

QFile (Basic)

Resource Files (.qrc)

QComboBox

QListWidget

QTreeWidget

QAction and Icon Resources

QStatusBar

QMessageBox

QTimer

QList

QListIterator

QMutableListIterator

QLinkedList

QMap

QHash

QStringList

QTextStream

QMimeType and QMimeDatabase

QFile (Serialization I)

QFile (Serialization II - Class)

Tool Tips in HTML Style and with Resource Images

QPainter

QBrush and QRect

QPainterPath and QPolygon

QPen and Cap Style

QBrush and QGradient

QPainter and Transformations

QGraphicsView and QGraphicsScene

Customizing Items by inheriting QGraphicsItem

QGraphicsView Animation

FFmpeg Converter using QProcess

QProgress Dialog - Modal and Modeless

QVariant and QMetaType

QtXML - Writing to a file

QtXML - QtXML DOM Reading

QThreads - Introduction

QThreads - Creating Threads

Creating QThreads using QtConcurrent

QThreads - Priority

QThreads - QMutex

QThreads - GuiThread

QtConcurrent QProgressDialog with QFutureWatcher

QSemaphores - Producer and Consumer

QThreads - wait()

MVC - ModelView with QListView and QStringListModel

MVC - ModelView with QTreeView and QDirModel

MVC - ModelView with QTreeView and QFileSystemModel

MVC - ModelView with QTableView and QItemDelegate

QHttp - Downloading Files

QNetworkAccessManager and QNetworkRequest - Downloading Files

Qt's Network Download Example - Reconstructed

QNetworkAccessManager - Downloading Files with UI and QProgressDialog

QUdpSocket

QTcpSocket

QTcpSocket with Signals and Slots

QTcpServer - Client and Server

QTcpServer - Loopback Dialog

QTcpServer - Client and Server using MultiThreading

QTcpServer - Client and Server using QThreadPool

Asynchronous QTcpServer - Client and Server using QThreadPool

Qt Quick2 QML Animation - A

Qt Quick2 QML Animation - B

Short note on Ubuntu Install

OpenGL with QT5

Qt5 Webkit : Web Browser with QtCreator using QWebView Part A

Qt5 Webkit : Web Browser with QtCreator using QWebView Part B

Video Player with HTML5 QWebView and FFmpeg Converter

Qt5 Add-in and Visual Studio 2012

Qt5.3 Installation on Ubuntu 14.04

Qt5.5 Installation on Ubuntu 14.04

Short note on deploying to Windows




Sponsor Open Source development activities and free contents for everyone.

Thank you.

- K Hong













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