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// Copyright (C) 2018 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
// **********************************************************************
// NOTE: the sections are not ordered by their logical order to avoid
// reshuffling the file each time the index order changes (i.e., often).
// Run the fixnavi.pl script to adjust the links to the index order.
// **********************************************************************
/*!
\previouspage creator-debugging-qml.html
\page creator-debugging-example.html
\nextpage creator-qml-debugging-example.html
\title Debugging a C++ Example Application
This section uses the \l{Creating a Qt Widget Based Application}{TextFinder}
example to illustrate how to debug Qt C++ applications in the
\uicontrol Debug mode.
TextFinder reads a text file into QString and then displays it with
QTextEdit. To look at the TextFinder class and see the stored data, place
a breakpoint in textfinder.cpp, as follows:
\list 1
\li Click in between the line number and the window border on the line
where we change the cursor position to set a breakpoint.
\image qtcreator-setting-breakpoint1.png
\li Select \uicontrol Debug > \uicontrol {Start Debugging} >
\uicontrol {Start Debugging of Startup Project} or press \key F5.
\li To view information about the breakpoint, go to the
\uicontrol Breakpoints view.
\image qtcreator-setting-breakpoint2.png
\li To remove a breakpoint, right-click it and select
\uicontrol {Delete Breakpoint}.
\li To view the base classes and data members of the TextFinder class,
go to the \uicontrol Locals view.
\image qtcreator-watcher.png
\endlist
Modify the \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. Add the following code snippet:
\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) {
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
If you compile and run the above code, however, the application does not
work correctly due to a logic error. To locate this logic error, step
through the code using the following buttons:
\inlineimage icons/qtcreator-debug-button-stop.png
(\uicontrol {Stop Debugger}), \inlineimage icons/debugger_stepover_small.png
(\uicontrol {Step Over}), \inlineimage icons/debugger_stepinto_small.png
(\uicontrol {Step Into}), and \inlineimage icons/debugger_stepout_small.png
(\uicontrol {Step Out}).
*/
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