qtcreator.qdoc

/*!
    \contentspage{index.html}{Qt Creator}
    \page index.html
    \nextpage creator-quick-tour.html

    \title Qt Creator Manual

    \section1 Version 0.9.1 (Beta)

    The goal of Qt Creator is to provide a cross-platform, complete Integrated
    Development Environment (IDE) to develop Qt projects. It is available for
    the Linux, Mac OS X and Windows platforms.

    \note The current version of Qt Creator is 0.9.1 (Beta). It is
    possible to edit source code, compile, run and debug applications; other
    features are still under development. Please send bug reports and
    suggestions to qt-creator@trolltech.com. To subscribe, send a
    message with the word \e subscribe to qt-creator-request@trolltech.com.
    For more information on Qt mailing lists, visit http://lists.trolltech.com

    \table
    \row
    \o \inlineimage qtcreator-screenshots.png
    \row
    \o Qt Creator includes a wide range of useful features. Among them are:
    \list 1
        \o \bold{Smart Code Editor}: The code editor provides syntax
            highlighting as well as code completion.
        \o \bold{Qt4 Project Generating Wizard}: This wizard allows the user
           to generate a project for a console application, a GUI application,
           or a C++ library.
        \o \bold{Qt Help Integration}: Qt's entire documentation can be
           accessed easily by clicking on the \gui{Help} button.
        \o \bold{Qt Designer Integration}: User interface forms can be designed
           within Qt Creator. Simply double-click on a \c{.ui} file within the
           \gui{Project Explorer} to launch the integration.
        \o \bold{Locator}: A powerful navigation tool that lets the user locate
           files and classes using minimal keystrokes.
        \o \bold{Support for qmake's .pro file format}: The project's \c{.pro}
           file is used as a project description file.
        \o \bold{Debugging Interface to GDB}: Applications can be debugged
           within Qt Creator using a graphical frontend to the GNU symbolic
           debugger.
    \endlist
    \endtable

    To learn more about the Qt Creator, click on one of the links below:

    \list
       \o \l{A Quick Tour of Qt Creator}
       \o \l{Creating a Project in Qt Creator}
       \o \l{Build Settings}
       \o \l{Writing a Simple Program with Qt Creator}
       \o \l{Navigating Quickly Around Your Code with Locator}
       \o \l{Debugging with Qt Creator}
       \o \l{Tips and Tricks}
       \o \l{Keyboard Shortcuts}
       \o \l{Glossary}
       \o \l{Known Issues of Version 0.9.1 (Beta)}
    \endlist

*/


/*!
    \contentspage index.html
    \page creator-quick-tour.html
    \nextpage creator-build-settings.html

    \title A Quick Tour of Qt Creator

    The labeled screenshot below shows some of the components of Qt Creator, in
    \gui Edit mode.

    \image qtcreator-breakdown.png

    \section1 The Mode Selectors

    When working in Qt Creator, you can be in one of six modes: \bold Welcome,
    \bold Edit, \bold Debug, \bold Projects, \bold Help, and \bold Output.

    Mode selectors allow you to quickly switch between tasks: Editing, browsing
    the Qt Creator manual, setting up the build environment, etc. You can
    activate a mode by either clicking on its mode selector, or using the
    \l{keyboard-shortcuts}{corresponding shortcut}. Certain actions also
    trigger a mode change, e.g., \gui{Debug}/\gui{Start Debugging} will switch
    to the \gui Debug mode.

    \list

    \o \gui{Welcome Mode} - Displays a welcome screen allowing you to quickly
    load recent sessions or individual projects. This is the mode you will see
    if Qt Creator is run without command line switches.

    \o \gui{Edit Mode} - Lets you edit both project and source files. A sidebar
    on the left provides different views to navigate between files.

    \o \gui{Debug Mode} - Provides various ways to inspect the state of the
    program while debugging. See \l{Debugging With Qt Creator} for a hands-on
    description of how to use this mode.

    \o \gui{Projects Mode} - Lets you configure how projects can be built and
    executed. Under the list of projects, there are tabs to configure the 
    build, run, and editor settings.

    \o \gui{Help Mode} - Shows any documentation registered by Qt Assistant,
    such as the Qt library and Qt Creator documentation.

    \o \gui{Output Mode} - Lets you examine various data in detail, for example
    build issues as well as compile and application output. This information
    is also available in the output panes.

    \endlist


    \section1 The Output Panes

    The task pane in Qt Creator can display one of four different panes:
    \gui{Build Issues}, \gui{Search Results}, \gui{Application Output}, and
    \gui{Compile Output}. These panes are available in all modes.

    \section2 Build Issues

    The {Build Issues} pane provides a list of issues, e.g., error messages or
    warnings that need to be fixed. It filters out irrelevant output from the
    compiler and collects them in an organized way.

    \image qtcreator-build-issues.png

    \section2 Search Results

    The \gui{Search Results} pane displays the results for global searches such
    as searching within a current document, files on disk, or all projects. In
    the screenshot below, we searched for all occurrences of \c{textfinder}
    within the \c{"/TextFinder"} folder.

    \image qtcreator-search-pane.png

    \section2 Application Output

    The \gui{Application Output} pane displays the status of the program when
    it is executed and debug output, e.g., output from qDebug().

    \image qtcreator-application-output.png

    \section2 Compile

    The \gui{Compile Output} pane provides all the output from the compiler. In
    other words, it is a more verbose version of information displayed in the
    \gui{Build Issues}

    \image qtcreator-compile-pane.png


    \section1 Session Management in Qt Creator

    ### screenshot

    In Qt Creator, a session is a collection of loaded projects, opened files,
    editor settings, and so on. When you run Qt Creator, you have a default
    session. You can create a new session using the \gui{Session Manager...},
    available in the \gui{File -> Session} menu.

    To switch between sessions, select \gui{File -> Session}. If you do not
    create and select any session, Qt Creator will always use the default
    session.

\omit
    session management can also store project dependencies, thorbjorn is
    currently working on it
\endomit


    \section1 Qt Help Integration

    Qt Creator comes fully integrated with all of Qt's documentation and
    examples via the Qt Help plugin. To view the documentation, you can switch
    to the \gui{Help} mode. To obtain context sensitive help, move your text
    cursor to a Qt class or function and press \key{F1}. The documentation
    will be displayed within a panel on the right, as shown in the screenshot
    below.

    External Documentation provided by the user can be used to augment or
    replace the documentation shipped with Qt Creator and Qt.

    \image qtcreator-context-sensitive-help.png


    \section1 Qt Designer Integration

    Qt Creator is fully integrated with Qt Designer to help you design user
    interface forms just like you would with the standalone version. The Qt
    Designer integration also includes project management and code completion.
    For more information on Qt Designer, you can refer to
    \l{http://doc.trolltech.com/designer-manual.html}{The Designer Manual}.

    \image qtcreator-formedit.png


    \section1 Keyboard Navigation
   
    Qt Creator caters not only to developers who are used to using the mouse,
    but also to developers who are more comfortable with the keyboard. A wide
    range of \l{keyboard-shortcuts}{keyboard} and
    \l{Navigating Quickly Around Your Code with Locator}{navigation} shortcuts
    are available to help speed up the process of developing your application.
*/


/*!
    \contentspage index.html
    \previouspage creator-quick-tour.html
    \page creator-build-settings.html
    \nextpage creator-creating-project.html

    \title Build Settings

    \table
        \row
            \i \note Qt Creator currently supports \c qmake only. \c Makefile
               and \c CMake support is currently unavailable.
    \endtable

    To modify the build settings of your project, switch to the \gui{Projects}
    mode using the mouse or with \key{Ctrl+4}.

    \image qtcreator-buildsettingstab.png

    Action items to create, clone, or delete build configurations can be found
    at the bottom of the dialog. You can have as many build configurations as
    needed. By default Qt Creator creates a \bold{debug} and \bold{release}
    build configuration. Both these configurations use the
    \l{glossary-default-qt}{Default Qt Version}.

    In the tree on the left, a list of build configurations and their settings
    are displayed. The screenshot above shows the \bold{debug} and
    \bold{release} configurations and their corresponding settings:
    \bold{Build Environment} and \bold{Build Steps}.

    When you select a build configuration in the tree, a configuration page for
    general build settings will be displayed. Here you can specify which
    \l{glossary-project-qt}{Qt version} to use to build your project, whether
    to \l{glossary-shadow-build}{shadow build} the project.

    \image qtcreator-buildenvironment.png

    In the \bold{Build Environment} page you can specify the environment used
    for building. By default the environment in which Qt Creator was started
    is used and modified to include the Qt version. Depending on the selected
    Qt version, Qt Creator will automatically add the necessary environment
    variables.

    \image qtcreator-buildsteps.png

    The build system of Qt Creator is built on top of \c qmake and \c make. The
    settings for \c qmake and \c make can be changed in the
    \bold{Build Settings} page. Qt Creator will run the make command using the
    correct Qt version.

    \note The \bold{Gdb Macros Build} step builds a small library along with your
    project that is used for the custom display of Qt and STL objects in the
    integrated debugger. The library is created and built in a "qtc-gdbmacros"
    subfolder of your project's main directory, and loaded dynamically into your
    application if you run it in the debugger. If the
    debugging helper seems to break your build or your application, you can
    remove the build step. You will still be able to debug applications, but the
    contents of Qt and STL data types will not be displayed properly.


    \section1 Qt Version Management

    Qt Creator allows you to use multiple versions of Qt installed on your hard
    disk and switch between them easily.

    Qt Creator automatically detects if \c qmake is in the environment variable
    \c PATH. This \l{glossary-system-qt}{version of Qt} is referred to as
    \bold{System Qt}. If you intend to use only one version of Qt - it is
    already in your path and correctly set up for command line usage - you do
    not need to manually configure your Qt version.

    Otherwise, you can add your Qt version in
    \gui{Tools -> Options... -> Qt Versions}. If you are on the Windows
    platform and use MinGW to compile Qt, you need to tell Qt Creator where
    MinGW is installed. This is done by setting the \gui{MinGW Directory}
    under \gui{Tools -> Options... -> Qt4 -> Qt Versions -> MinGw Directory}.
    If your Qt version is compiled with Microsoft Visual C++'s compiler, Qt
    Creator will automatically set the correct environment variables for
    compilation.

    \note By default projects are compiled with the
    \l{glossary-default-qt}{default Qt version}. You can override this in the
    \gui{Build Configuration}.
*/


/*!
    \contentspage index.html
    \previouspage creator-quick-tour.html
    \page creator-creating-project.html
    \nextpage creator-writing-program.html

    \title Creating a Project in Qt Creator

    \table
        \row
	    \i \inlineimage qtcreator-new-project.png
            \i \bold{Creating a New Project}

        To create a new project, select \gui{New Project} from the \gui{File} menu.
        You can create one of the following three projects:
    
        \list
            \o Qt4 Console Application
            \o Qt4 Gui Application
            \o C++ Library
        \endlist

        In this example, we select a \e{Qt4 Gui Application} and click \gui{OK}.

        \row
	    \i \inlineimage qtcreator-intro-and-location.png
            \i \bold{Setting the Project name and location}

        Next, we set the project's name and its path. Click on the \gui{...}
        button to browse and select your path.

        Ideally, the path should not contain spaces or special characters.

        \row
	    \i \inlineimage qtcreator-select-modules.png
            \i \bold{Selecting The Necessary Qt Modules}

        Click on the check boxes of each Qt Module you would like to include in
        your project.

        Since we started a Qt4 Gui Application, the Core and Gui modules are
        set, but you are free to add more.

        \row
	    \i \inlineimage qtcreator-class-info.png
            \i \bold{Specifying Class Information}

        Specify the name of the class you would like to create. The
        \e{Header file}, \e{Source file} and \e{Form file} fields will update
        automatically according to your choice of class name.

        You also have to select the base class for your class, either a
        QWidget, QDialog or QMainWindow,  from the drop down box.

        \row
	    \i \inlineimage qtcreator-new-project-summary.png
            \i \bold{Creating the Project}

        Finally, review the files that will be created for you. Click
        \gui{Done} and your project will be generated.
    
    \endtable
*/


/*!
    \contentspage index.html
    \previouspage creator-creating-project.html
    \page creator-writing-program.html
    \nextpage creator-navigation.html

    \title Writing a Simple Program with Qt Creator

    \table
        \row
        \o \note This tutorial assumes that the user has experience writing
           basic Qt applications, designing user interfaces with Qt Designer
           and and using the Qt Resource System.
    \endtable


    In this example, we will describe the steps involve in using Qt Creator
    to create a small Qt program, Text Finder. Inspired by the QtUiTools'
    \l{http://doc.trolltech.com/uitools-textfinder.html}{Text Finder}
    example, we will write a similar but simplified version of it, as shown
    below.

    \image qtcreator-textfinder-screenshot.png

    \section1 Setting Up Your Environment

    Once you have installed Qt Creator, it will automatically detect if Qt's
    location is in your \c PATH variable. If Qt's location is not in your
    \c PATH, you can set it in one of the following ways, depending on your
    platform:

    \list
         \o On Windows and Linux: in the \gui{Tools} menu, under \gui{Options}.
         \o On Mac OS X: in \gui{Preferences}, under \gui{Qt4}.
    \endlist

    \note If Qt was compiled with Visual Studio, all environment variables set
    in Visual Studio will be added to Qt Creator as well.

    \section1 Setting Up The Project

    We begin with a Qt4 Gui Application project generated by Qt Creator. The
    \l{Creating a Project in Qt Creator} document describes this process in
    detail. Remember to select QWidget as the Text Finder's base class. If
    your project is not yet loaded, you can load it by selecting \gui{Open}
    from the \gui{File} menu.

    In your project you will have the following files:

    \list
        \o \c{textfinder.h}
        \o \c{textfinder.cpp}
        \o \c{main.cpp}
        \o \c{textfinder.ui}
        \o \c{textfinder.pro}
    \endlist
    
    The \c{.h} and \c{.cpp} files come with the necessary boiler plate code;
    the \c{.pro} file is also complete.

    \section1 Filling In The Missing Pieces

    We will begin by designing the user interface and then move on to filling
    in the missing code. Finally, we will add the find functionality.

    \section2 Designing the User Interface

    To begin designing the user interface, double-click on the
    \c{textfinder.ui} file in your \gui{Project Explorer}. This will launch the
    integrated Qt Designer.

    \image qtcreator-textfinder-ui.png

    Design the form above using a \l{http://doc.trolltech.com/qlabel.html}
    {QLabel}, \l{http://doc.trolltech.com/qlinedit.html}{QLineEdit},
    \l{http://doc.trolltech.com/qpushbutton.html}{QPushButton} and a
    \l{http://doc.trolltech.com/qtextedit.html}{QTextEdit}. We recommend that
    you use a QGridLayout to lay out the
    \l{http://doc.trolltech.com/qlabel.html}{QLabel},
    \l{http://doc.trolltech.com/qlinedit.html}{QLineEdit} and
    \l{http://doc.trolltech.com/qpushbutton.html}{QPushButton}. The
    \l{http://doc.trolltech.com/qtextedit.html}{QTextEdit} can then be added to
    a \l{http://doc.trolltech.com/qvboxlayout.html}{QVBoxLayout}, along with
    the \l{http://doc.trolltech.com/qgridlayout.html}{QGridLayout}. If you are
    new to designing forms with \QD, you can take a look at the 
    \l{http://doc.trolltech.com/designer-manual.html}{Designer Manual}.

    \section2 The Header File

    The \c{textfinder.h} file already has the necessary includes, a
    constructor, a destructor, and the \c{Ui} object. We need to add a private
    slot, \c{on_findButton_clicked()}, to carry out our find operation. We
    also need a private function, \c{loadTextFile()}, to read and display the
    contents of our input text file in the
    \l{http://doc.trolltech.com/qtextedit.html}{QTextEdit}. This is done with
    the following code:

    \code
    private slots:
        void on_findButton_clicked();

    private:
        Ui::Form ui;
        void loadTextFile();
    \endcode

    \note The \c{Ui::Form} object is already provided.

    \section2 The Source File

    Now that our header file is complete we move on to our source file,
    \c{textfinder.cpp}.  We begin by filling in the functionality to load a
    text file. The code snippet below describes this:

    \code
    void TextFinder::loadTextFile()
    {
        QFile inputFile(":/input.txt");
        inputFile.open(QIODevice::ReadOnly);
        
        QTextStream in(&inputFile);
        QString line = in.readAll();
        inputFile.close();
        
        ui.textEdit->setPlainText(line);
        QTextCursor cursor = ui.textEdit->textCursor();
    }
    \endcode

    Basically, we load a text file using
    \l{http://doc.trolltech.com/qfile.html}{QFile}, read it with
    \l{http://doc.trolltech.com/qtextstream.html}{QTextStream}, and
    then display it on \c{textEdit} with
    \l{http://doc.trolltech.com/qtextedit.html#plainText-prop}{setPlainText()}.

    For the \c{on_findButton_clicked()} slot, we extract the search string and
    use the \l{http://doc.trolltech.com/qtextedit.html#find}{find()} function
    to look for the search string within the text file. The code snippet below
    further describes it:

    \code
    void TextFinder::on_findButton_clicked()
    {
        QString searchString = ui.lineEdit->text();
        ui.textEdit->find(searchString, QTextDocument::FindWholeWords);
    }
    \endcode

    Once we have both these functions complete, we call \c{loadTextFile()} in
    our constructor.

    \code
    TextFinder::TextFinder(QWidget *parent, Qt::WFlags flags)
        : QWidget(parent, flags)
    {
        ui.setupUi(this);
        loadTextFile();
    }
    \endcode

    The \c{on_findButton_clicked()} slot will be called automatically due to
    this line of code:

    \code
    QMetaObject::connectSlotsByName(Form);
    \endcode

    in the uic generated \c{ui_textfinder.h} file.

    \section2 The Resource File

    We require a resource file (\c{.qrc}) within which we will embed the input
    text file. This can be any \c{.txt} file with a paragraph of text. To add
    a resource file, right click on \gui{Resource Files} in the
    \gui{Project Explorer} and select \gui{Add New File...}. You will see the
    wizard dialog displayed below.

    \image qtcreator-add-resource-wizard.png

    Enter "textfinder" in the \gui{Name} field and use the given \gui{Path}.
    Then, click \gui{Continue}.

    \image qtcreator-add-resource-wizard2.png

    On this page you can choose to which project you want to add the new file.
    Make sure that \gui{Add to Project} is checked and
    "TextFinder" is selected as the \gui{Project}, and click
    \gui{Done}.

    Your resource file will now be displayed with the Resource Editor. Click
    on the \gui{Add} drop down box and select \gui{Add Prefix}. The prefix we
    require is just a slash (\c{/}). Click \gui{Add} again but this time,
    select \gui{Add File}. Locate the text file you are going to use, we use
    \c{input.txt}.

    \image qtcreator-add-resource.png

    The screenshot above shows what you can expect to see once you have added
    the resource file successfully.

    \section1 Compiling and Running Your Program

    Now that you have all the necessary files, you can compile your program by
    clicking on the 
    \inlineimage qtcreator-run.png
    button.
    
*/


/*!
    \contentspage index.html
    \previouspage creator-writing-program.html
    \page creator-navigation.html
    \nextpage creator-debugging.html

    \title Navigating Quickly Around Your Code with Locator

    With Qt Creator, navigating to different locations in your project or on
    your disk, e.g., files, classes, methods, etc., is trivial using
    \gui Locator -- a smart line edit at the bottom left of Qt Creator's
    window.

    \image qtcreator-locator.png

    Suppose you would like to open your project's \c{main.cpp} file, click on
    \gui Locator or use \key{Ctrl+K}, type in the file name and then press
    \key Return. The file will be opened in the editor. You can also type
    part of a file name and use wildcard characters \c{*} and \c{?} to match
    \e{any} number of \e{any} characters. A list of all files matching your
    criteria will be displayed. 

    \gui Locator not only allows you to navigate files on disk but also other
    "locations", which are organized with \bold{Filters}. Currently there are
    filters for:

    \list
        \o  files anywhere on your hard disk (browsing through the file system),
        \o  files from a subdirectory structure defined by you,
        \o  files mentioned in your \c{.pro} files, such as source, header,
            resource, and \c{.ui} files,
        \o  any open document,
        \o  class and method definitions in your project or anywhere referenced
            from your project,
        \o  help topics, including Qt's documentation, and,
        \o  a specific line in the document displayed on your editor,
    \endlist


    Some of these filters require you to activate them by typing an assigned
    \e prefix. This prefix is usually a single character followed by
    \key{Space}. For example, to jump to the definition of the class
    \l{http://doc.trolltech.com/qdatastream.html}{QDataStream}, type:
    \key{Ctrl+K} to activate \gui Locator. Then type colon (\key{:}) followed
    by \key{Space} and the class name.


    Below is a full list of \l{http://doc.trolltech.com/qdatastream.html}
    {QDataStream} related output:

    \image qtcreator-navigate-popup.png


    Filters can be added to provide quick navigation around files in a
    subdirectory structure defined by you. This way, you can acccess files you
    need, that are not directly mentioned in your project. Click on 
    \image qtcreator-locator-magnify.png
     and choose \gui{Configure...} from the menu displayed.

    \image qtcreator-locator-customize.png

    This then displays the \gui Preferences dialog (\gui Options on Mac Os X)
    for navigation filters. Click \gui Add to create a new filter. In the
    \gui{Filter Configuration} dialog below, give your filter a name, select
    your preferred directories, set file patterns with a comma separated list,
    and specify a prefix string.

    \image qtcreator-navigate-customfilter.png

    After closing this dialog, \gui Locator will search the directories you
    selected for files matching your file patterns, and the information will be
    cached. Click \gui Refresh from the menu above to update the cached
    information.

    The following table lists the filters currently available:

    \table
        \header
            \o  Function
            \o  Key Combination
            \o  Screenshot
        \row
            \o  Go to a line in the current document
            \o  Ctrl+K, l, Space, and the line number
            \o  \image qtcreator-locator-line.png
        \row
            \o  Go to a symbol definition
            \o  Ctrl+K, :, Space, and the function name
            \o  \image qtcreator-locator-symbols.png
        \row
            \o  Go to a help topic
            \o  Ctrl+K, ?, Space, and the topic
            \o  \image qtcreator-locator-help.png
        \row
            \o  Go to an opened document
            \o  Ctrl+K, o, Space, and the document name.
            \o  \image qtcreator-locator-opendocs.png
        \row
            \o  Go to a file in the file system (browse the file system)
            \o  Ctrl+K, f, Space, and the file name.
            \o  \image qtcreator-locator-filesystem.png
        \row
            \o  Go to a file in any project currently loaded
            \o  Ctrl+K, a, Space, and the function name.
            \o  \image qtcreator-locator-files.png
        \row
            \o  Go to a file in the current project
            \o  Ctrl+K, p, Space, and the function name.
            \o  \image qtcreator-locator-current-project.png
        \row
            \o  Go to a class definition
            \o  Ctrl+K, c, Space, and the class name.
            \o  \image qtcreator-locator-classes.png
        \row
            \o  Go to a method definition
            \o  Ctrl+K, m, Space, and the class name.
            \o  \image qtcreator-locator-methods.png
    \endtable

    \note By default, if you press \key{Ctrl+K} and do not use a prefix to
    specify a filter, three filters will be enabled: \c{o}, \c{l}, and \c{a}.

*/


/*!
    \contentspage index.html
    \previouspage creator-navigation.html
    \page creator-debugging.html
    \nextpage creator-tips.html

    \title Debugging with Qt Creator

    \table
        \row 
            \i \note Qt Creator's debugger integration currently does not
               support debugging applications created with the Microsoft Visual
               Studio Compiler.
    \endtable

    Qt Creator does not have its own debugger. Instead, it provides a graphical
    frontend to the GNU Symbolic Debugger (gdb). This frontend allows you to
    step through a program line-by-line or instruction-by-instruction,
    interrupt running programs, set breakpoints, examine the contents of the
    call stack, local and global variables, etc.


    Within Qt Creator, the raw information provided by gdb is displayed in a
    clear and concise manner, simplifying the process of debugging.

    In addition to generic IDE functionality: stack view, views for locals and
    watchers, registers, etc, Qt Creator comes with additional features to make
    debugging Qt-based applications easy. The debugger frontend knows about the
    internal layout of several Qt classes such as QString, the QTL containers,
    and most importantly QObject (and classes derived from it). Therefore, it
    is able to present Qt's data clearly.


    \section1 Interacting with the Debugger

    In \gui Debug mode, several dock widgets are used to interact with the
    program you are debugging. The frequently used dock widgets are visible by
    default; the rarely used ones are hidden. To change the default settings,
    select \gui Debug and then select \gui View.

    \image qtcreator-debug-view.png

    Here, you can lock or unlock the location of your views as well as display
    or hide them. Among the views you can display are \gui Breakpoints,
    \gui Disassembler, \gui Modules, \gui Registers, \gui Gdb, \gui Stack, and
    \gui Thread. The position of your dock widgets will be saved for future
    sessions.


    \section2 Breakpoints

    Breakpoints are shown in the \gui{Breakpoints} view which is enabled by
    by default. This view is also accessible when the debugger and the program
    being debugged is not running.

    A breakpoint represents a position or sets of positions in the code that,
    when executed, stops the program being debugged and passing the control to
    the user. The user is then free to examine the state of the interrupted
    program, or continue execution line-by-line or continuously.

    Typically, breakpoints are associated with a source code file and line, or
    the start of a function -- both allowed in Qt Creator.

    Also, the interruption of a program by a breakpoint can be restricted with
    certain conditions.

    You can set a breakpoint:

    \list
       \o At a particular line you want the program to stop -- click on the
          left margin or press \key F9 (\key F8 for Mac OS X).
       \o At a function that you want the program to stop -- enter the
          function's name in \gui{Set Breakpoint at Function...} under the
          \gui Debug menu.
    \endlist

    You can remove a breakpoint:

    \list
        \o By clicking on the breakpoint marker in the text editor.
        \o By selecting the breakpoint in the breakpoint view and pressing
           \key{Delete}.
        \o By selecting \gui{Delete Breakpoint} from the breakpoint's context
           menu in the \gui Breakpoints view.
    \endlist

    Breakpoints can be set and deleted before the program has actually started
    running or while it is running under the debugger's control. Also,
    breakpoints are saved together with a session.


    \section2 Running

    To start a program under the debugger's control, select the \gui{Debug}
    menu and \gui{Start Debugging}, or simply press \key{F5}. Qt Creator then
    checks whether the compiled program is up-to-date, rebuilding it if
    necessary. The debugger then takes over and starts the program.

    \note Starting a program in the debugger will take considerable amount of
    time, typically in the range of several seconds to minutes if complex
    features (like QtWebKit) are used. 

    Once the program starts running, it behaves as usual; performance-wise as
    well. The user can interrupt a running program by selecting
    \gui {Interrupt} from the \gui{Debug} menu. The program is automatically
    interrupted as soon as a breakpoint is hit.

    \omit (and, if set, its associated conditions are met). \endomit

    Once the program stops, Qt Creator:

    \list
        \o Retrieves data representing the call stack at the program's current
           position.
        \o Retrieves the contents of local variables.
        \o Examines \gui Watchers.
        \o Updates the \gui Registers, \gui Modules, and \gui Disassembler
           views.
    \endlist


    You can use the debugger views to examine the data in more detail.

    To finish debugging, Press \key{Shift+F5}. A line of code can be executed
    as a whole with \key F10; to execute a function or a sub-function, use
    \key F11. Alternatively, you can continue running the program with \key F5.
    It is possible to continue executing your program until the current
    function completes or jump to an arbitrary position in the current
    function.


    \section2 Stack

    When the program being debugged is stopped, Qt Creator displays the nested
    function calls leading to the current position as a \e call stack trace.
    This stack trace is built up from \e{call stack frames}, each representing a
    particular function. For each function, Qt Creator will try to retrieve the
    file name and line number of the corresponding source files. This data is
    shown in the \gui Stack view.

    \image qtcreator-debug-stack.png

    Since the call stack leading to the current position may originate or go
    through code for which no debug information is available, not all stack
    frames will have corresponding source locations. These frames will be
    greyed out in the \gui Stack view.

    If you click on a frame with a known source location, the text editor will
    jump to the corresponding location and update the \gui{Locals and Watchers}
    view, making it seem like the program stopped before entering the function.


    \section2 Threads

    If a multi-threaded program is stopped, the \gui Thread view  or the
    combobox named \gui Thread in the debugger's status bar can be used to
    switch from one thread to another. The \gui Stack view will adjust itself
    accordingly.


    \section2 Locals and Watchers

    Whenever a program stops under the control of the debugger, it retrieves
    information about the topmost stack frame and displays it in the
    \gui{Locals and Watchers} view. This typically includes information about
    parameters of the function in that frame as well as the local variables.

    Compound variables of struct or class type will be displayed as
    "expandable" in the view. C lick on the "+" to expand the entry and show
    all members. Together with the display of value and type, the user can
    examine and traverse the low-level layout of an object's data.


    \table
        \row
            \i \bold{Note:}

            \i  Gdb, and therefore Qt Creator's debugger works for optimized
                builds on Linux and Mac OS X. However, optimization may lead
                to re-ordering of instructions or sometimes even complete
                removal of some local variables. In this case, the
                \gui{Locals and Watchers} view may show unexpected data.

            \i  The debug information provided by gcc does not include enough
                information about the time when a variable is initialized.
                Qt Creator therefore can not tell whether the contents of a
                local variable contains "real data", or "initial noise". If a
                QObject appears uninitialized, its value will be reported as
                "out of scope". However, not all uninitialized objects can be
                recognized as such.
    \endtable


    The \gui{Locals and Watchers} view also provides access to the most
    powerful feature of the debugger: comprehensive display of data belonging
    to Qt's basic objects. To enable this feature, select \gui{Use Custom
    Display for Qt Objects} from the \gui Debug menu.The
    \gui{Locals and Watchers} view will be re-organized to provide a high-level
    view of the objects. For example, in case of QObject, instead of displaying
    a pointer to some private data structure, you will see a list of children,
    signals and slots.

    Similarly, instead of displaying many pointers and integers, Qt Creator's
    debugger will display the contents of a QHash or QMap in an orderly manner.
    Also, the debugger will display access data for QFileInfo and provide
    access to the "real" contents of QVariant.

    The \gui{Locals and Watchers} view can be used to change the contents of
    variables of simple data types such as \c int or \c float when the program
    is stopped. To do so, click on the \gui Value column, modify the value
    with the inplace editor, and hit \key Enter (or \key Return).
    

    \section2 Modules

    By default, the \gui Modules view is hidden as it is only useful with the
    experimental delayed loaing of debug information feature. You can turn
    this feature on by selecting \gui{Fast Debugger Start} 


    With this feature, debug information from the Qt library itself is not
    loaded when the application starts up, thereby reducing the startup times
    for some applications. You can then use the \gui Modules view to manually
    load this information, if required.

    \note In this scenario, some breakpoints may not be set by the debugger.

        
    \section2 Disassembler View and Registers View

    By default, both the \gui Disassembler and \gui Registers view are hidden.
    The \gui Disassembler view displays disassembled code for the current
    function; the \gui Registers view displays the current state of the CPU's
    registers. Both views are useful for low-level commands such as
    \gui{Step Single Instruction} and \gui{Step Over Single Instruction}.

    \section1 A Walkthrough for the Debugger Frontend

    In our \l{Writing a Simple Program with Qt Creator}{TextFinder} example, we
    read a text file into a QString and then display it with a QTextEdit.
    Suppose, you would like to look at this QString, \c{line}, and see what
    data it actually stores. Follow the steps described below to place a
    breakpoint and view the QString object's data.

    \table
        \row
	        \i \inlineimage qtcreator-setting-breakpoint1.png
            \i \bold{Setting a Breakpoint}

    First, we set a breakpoint on the line where we invoke
    \l{http://doc.trolltech.com/qtextedit.html#plainText-prop}{setPlainText()}
    by clicking between the line number and the window border. Then, select
    \gui{Start Debugging} from the \gui{Debug} menu or press \key{F5}.
    \endtable

    Breakpoints are visible in the \gui{Breakpoints} view, shown below, in
    \gui{Debug} mode. If you wish to remove a breakpoint, simply right-click on
    it and select \gui{Delete breakpoint} from the context menu.

    \image qtcreator-setting-breakpoint2.png

    To view the contents of \c{line}, take a look at the \gui{Locals and
    Watchers} view.

    \image qtcreator-watcher.png

    Suppose we modify our \c{on_findButton_clicked()} function to move back to
    the start of the document and continue searching once the cursor hits the
    end of the document. Adding this functionality can be done with the code
    snippet below:

    \code
    void TextFinder::on_findButton_clicked()
    {
        QString searchString = ui.lineEdit->text();

        QTextDocument *document = ui.textEdit->document();
        QTextCursor cursor = ui.textEdit->textCursor();
        cursor = document->find(searchString, cursor,
            QTextDocument::FindWholeWords);
        ui.textEdit->setTextCursor(cursor);

        bool found = cursor.isNull();

        if (!found && previouslyFound == true) {
            int ret = QMessageBox::question(this, tr("End of Document"),
            tr("I have reached the end of the document. Would you like "
            "me to start searching from the beginning of the document?"),
            QMessageBox::Yes | QMessageBox::No, QMessageBox::Yes);

            if (ret == QMessageBox::Yes) {
                cursor = document->find(searchString,
                    QTextDocument::FindWholeWords);
                ui.textEdit->setTextCursor(cursor);
            } else
                return;
        }
        previouslyFound = found;
    }
    \endcode

    However, if you compile and run this code, the application will not work
    correctly due to a logic error. To locate this logic error, you can step
    through the code using the following buttons: