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Application Development with Qt Creator - Second Edition
Application Development with Qt Creator - Second Edition

Application Development with Qt Creator - Second Edition: Design and build dazzling cross-platform applications using Qt and Qt Quick , Second Edition

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Application Development with Qt Creator - Second Edition

Chapter 2. Building Applications with Qt Creator

The first thing you would want to do with Qt Creator is figure out how to add source files and build (or debug) your project. This chapter is all about that—we'll go over how to add files to a project, how to create libraries in a project, and how to use the debugger and the console logger. At the end of this chapter, you'll be driving Qt Creator to develop console applications like a pro.

In this chapter, we will do the following:

  • Learn about our sample library
  • Look into the Build menu and the .pro files
  • Link against our sample library
  • Debug
  • Build your project
  • Run and debug your application

Getting started – our sample library

This chapter's example code has two pieces: a library that defines a public function and a console application that calls this function. Libraries are a great way to break up your applications, and while this example is simple, it also lets me show you how to create a library and include it in your application.

I'm going to stretch your imagination a bit; let's pretend that you're responsible for setting up a library of math functions. In this example, we'll only write one function, factorial. You should be able to recollect the factorial function from introductory programming; it's represented by a ! and is defined as follows:

  • 0! is 0
  • 1! is 1
  • n! is n × (n - 1)!

This is a recursive definition and we can code it in the following way:

unsigned long factorial(unsigned int n)
{
    switch(n) 
    {
        case 0: return 0;
        case 1: return 1;
        default: return n * factorial(n-1);
    }
}

An alternate definition...

Learning the landscape – the Build menu and the .pro files

In the previous chapter, you learned how to build applications by hitting the hammer button in the corner of Qt Creator's main window or by starting the debugger. To just build your library—or any application—you can either use the hammer icon or the various choices in the Build menu. The obvious choice is either Build All or Rebuild All; choosing Build All recompiles only those files that need to be rebuilt as recognized by Qt Creator; Rebuild All cleans the project of all the object files and rebuilds the entire project from scratch. In most cases, it's sufficient to choose Build All, and that's what you want to do because it's faster. Sometimes, you really do want to rebuild the whole project, when things are broken and Qt's Make system can't reconcile all the dependencies (or you've incorrectly specified them). Select Build All now and wait for it to build while we discuss...

Linking against our sample library

Now, let's make an application that depends on our library. Our application will call the factorial function in the library, statically linking to the library in order to access the factorial function. To accomplish this, you need to perform the following steps:

  1. Select Close All Projects and Editors from the File menu.
  2. Choose New File or Project… from the File menu and create a new Qt console application called MathFunctionsTest using the wizard.
  3. Right-click on MathFunctionsTest in the Project pane and click on Add Library.... You can now choose a library in your build tree, a library outside your build tree, an external library on your system such as the Unix math library, fftmpeg, or another library that you've created. Select External Library and click on Next.
  4. Browse the library file that was built in the previous section by clicking on Browse, next to the line labelled Library file. It'll be in a folder named something such as build...

Getting lost and found again – debugging

Qt Creator has a state-of-the-art GUI that hooks into either the GNU debugger GDB, or Microsoft's command-line debugger CDB if you use Microsoft tools.

If you've installed Qt Creator on Mac OS or Linux or the MinGW version of Qt Creator for Windows, you have everything you need to begin debugging your application. If you already had Microsoft Visual Studio installed and then installed a version of Qt Creator that uses Microsoft's compiler, you also need to install the Microsoft command-line debugger to use Qt Creator's debugging features. Here's how you can install the command-line debugger:

  1. Download the debugging tools for Windows, either from http://msdn.microsoft.com/en-us/windows/hardware/hh852365 if you are using the 32-bit version of the compiler and Qt Creator, or from http://msdn.microsoft.com/en-us/windows/hardware/hh852365 for the 64-bit version of the compiler and Qt Creator.
  2. Configure the debugging symbol...

The Projects pane and building your project

You've seen how the .pro file affects your project's compilation, but there's even more to it than this. If you click on the Projects button on the left of Qt Creator, you'll see the project's options, which consist of the following:

  • The Build & Run options
  • The Editor options
  • The Code Style options
  • Dependencies

Each of these is in its own panel.

Note

In most cases, you won't need to monkey around with any of these settings. But you might have to tinker with the Build & Run settings, especially if you're targeting multiple platforms such as Windows and Linux with cross-compilers or Android. (I will write more about this exciting development in Qt later in this book.)

The final thing that you should know is the build and run kit selector. Qt is one of the best cross-platform toolkits available today, and you can easily find yourself working on a system supporting multiple platforms, such as Linux and Android, or...

Getting started – our sample library


This chapter's example code has two pieces: a library that defines a public function and a console application that calls this function. Libraries are a great way to break up your applications, and while this example is simple, it also lets me show you how to create a library and include it in your application.

I'm going to stretch your imagination a bit; let's pretend that you're responsible for setting up a library of math functions. In this example, we'll only write one function, factorial. You should be able to recollect the factorial function from introductory programming; it's represented by a ! and is defined as follows:

  • 0! is 0

  • 1! is 1

  • n! is n × (n - 1)!

This is a recursive definition and we can code it in the following way:

unsigned long factorial(unsigned int n)
{
    switch(n) 
    {
        case 0: return 0;
        case 1: return 1;
        default: return n * factorial(n-1);
    }
}

An alternate definition that avoids the cost of function calls...

Learning the landscape – the Build menu and the .pro files


In the previous chapter, you learned how to build applications by hitting the hammer button in the corner of Qt Creator's main window or by starting the debugger. To just build your library—or any application—you can either use the hammer icon or the various choices in the Build menu. The obvious choice is either Build All or Rebuild All; choosing Build All recompiles only those files that need to be rebuilt as recognized by Qt Creator; Rebuild All cleans the project of all the object files and rebuilds the entire project from scratch. In most cases, it's sufficient to choose Build All, and that's what you want to do because it's faster. Sometimes, you really do want to rebuild the whole project, when things are broken and Qt's Make system can't reconcile all the dependencies (or you've incorrectly specified them). Select Build All now and wait for it to build while we discuss the other options.

The Build menu lets you build a single...

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Description

This book is great for developers who are new to Qt and Qt Creator and who are interested in harnessing the power of Qt for cross-platform development. If you have basic experience programming in C++, you have what it takes to create engaging cross-platform applications using Qt and Qt Creator!

Product Details

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Publication date, Length, Edition, Language, ISBN-13
Publication date : Nov 27, 2014
Length: 264 pages
Edition : 2nd
Language : English
ISBN-13 : 9781784398675
Vendor :
Qt
Category :
Languages :
Tools :

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Product Details

Publication date : Nov 27, 2014
Length: 264 pages
Edition : 2nd
Language : English
ISBN-13 : 9781784398675
Vendor :
Qt
Category :
Languages :
Tools :

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Table of Contents

14 Chapters
1. Getting Started with Qt Creator Chevron down icon Chevron up icon
2. Building Applications with Qt Creator Chevron down icon Chevron up icon
3. Designing Your Application with Qt Designer Chevron down icon Chevron up icon
4. Qt Foundations Chevron down icon Chevron up icon
5. Developing Applications with Qt Widgets Chevron down icon Chevron up icon
6. Drawing with Qt Chevron down icon Chevron up icon
7. Doing More with Qt Quick Chevron down icon Chevron up icon
8. Multimedia and Qt Quick Chevron down icon Chevron up icon
9. Sensors and Qt Quick Chevron down icon Chevron up icon
10. Localizing Your Application with Qt Linguist Chevron down icon Chevron up icon
11. Optimizing Performance with Qt Creator Chevron down icon Chevron up icon
12. Developing Mobile Applications with Qt Creator Chevron down icon Chevron up icon
13. Qt Tips and Tricks Chevron down icon Chevron up icon
Index Chevron down icon Chevron up icon

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(25 Ratings)
5 star 44%
4 star 28%
3 star 8%
2 star 20%
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Valdemar Katayama Kjaer Dec 31, 2014
Full star icon Full star icon Full star icon Full star icon Full star icon 5
It's an ideal beginner's guide. If you want an advanced QT book, this one is not for you.
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morpheus_bd Aug 27, 2017
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Good Book.
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Dave G Jul 21, 2017
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does a body good to recommend a book based on subject. This is a new-ish book on the closest thing that C/C++ has to actual Rapid Application Development (RAD). This is very important to me as I don't have time to build a GUI in guile and map everything to something in languages like python. I like my speed, I like my C++ and my GUI without endless macros and junk in the libraries (in order, Windows, Gtk, Boost). When I have a need for a program, I don't have time to design it. I put the functionality on a window and clean it up later. I'm a programmer not a manager, so I know that most of what I need to do is in the background. Once it functions, I pretty it up. QtCreator is not Java and is not based on Java, so the IDE and compiler are very fast.
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eric c. Jul 18, 2018
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fantastic book!
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Wim Van Loocke Jan 21, 2015
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This is a good book on how to use QtCreator. It focuses on how to create GUI and doesn't overkill with repeating on Qt class description/functionality you can find on the qt website. It really helps in quickly "hands-on" GUI creation. Understandable for newbies. A must have!
Amazon Verified review Amazon
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