C++/Qt/QFile
Содержание
- 1 Check file existance and file name with QFile
- 2 Create file with QFile
- 3 Create QFile from file path
- 4 Open a text file in read-only mode
- 5 Open binary file for write-operation
- 6 Open QFile with WriteOnly flag
- 7 Open text file for write-operation
- 8 Output with QFile
- 9 Read byte array from text file
- 10 Read file till file end
- 11 Read text file line by line
Check file existance and file name with QFile
Foundations of Qt Development\Chapter08\fileexist\main.cpp
/*
* Copyright (c) 2006-2007, Johan Thelin
*
* All rights reserved.
*
* 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 APress 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.
*
*/
#include <QFile>
#include <QtDebug>
int main( int argc, char **argv )
{
QFile file( "testfile.txt" );
if( !file.exists() )
{
qDebug() << "The file" << file.fileName() << "does not exist.";
return 0;
}
if( !file.open( QIODevice::WriteOnly ) )
{
qDebug() << "Could not open" << file.fileName() << "for writing.";
return 0;
}
qDebug() << "The file opened.";
file.close();
return 0;
}
Create file with QFile
Foundations of Qt Development\Chapter08\datastream\main.cpp
/*
* Copyright (c) 2006-2007, Johan Thelin
*
* All rights reserved.
*
* 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 APress 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.
*
*/
#include <QFile>
#include <QDataStream>
#include <QList>
#include <QColor>
#include <QtDebug>
struct ColorText
{
QString text;
QColor color;
};
QDataStream &operator<<( QDataStream &stream, const ColorText &data )
{
stream << data.text << data.color;
return stream;
}
QDataStream &operator>>( QDataStream &stream, ColorText &data )
{
stream >> data.text;
stream >> data.color;
return stream;
}
void saveList()
{
QList<ColorText> list;
ColorText data;
data.text = "Red";
data.color = Qt::red;
list << data;
data.text = "Blue";
data.color = Qt::blue;
list << data;
data.text = "Yellow";
data.color = Qt::yellow;
list << data;
data.text = "Green";
data.color = Qt::green;
list << data;
QFile file( "test.dat" );
if( !file.open( QIODevice::WriteOnly ) )
return;
QDataStream stream( &file );
stream.setVersion( QDataStream::Qt_4_2 );
stream << list;
file.close();
}
void loadList()
{
QList<ColorText> list;
QFile file( "test.dat" );
if( !file.open( QIODevice::ReadOnly ) )
return;
QDataStream stream( &file );
stream.setVersion( QDataStream::Qt_4_2 );
stream >> list;
file.close();
foreach( ColorText data, list )
qDebug() << data.text << "("
<< data.color.red() << ","
<< data.color.green() << ","
<< data.color.blue() << ")";
}
int main( int argc, char **argv )
{
saveList();
loadList();
return 0;
}
Create QFile from file path
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QFile>
#include <QTextStream>
static void process_line(const QByteArray &)
{
}
static void process_line(const QString &)
{
}
int main()
{
QFile file("in.txt");
if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
return 1;
while (!file.atEnd()) {
QByteArray line = file.readLine();
process_line(line);
}
}
Open a text file in read-only mode
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QFile>
#include <QTextStream>
static void process_line(const QByteArray &)
{
}
static void process_line(const QString &)
{
}
int main()
{
QFile file("in.txt");
if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
return 1;
while (!file.atEnd()) {
QByteArray line = file.readLine();
process_line(line);
}
}
Open binary file for write-operation
#include <QFile>
#include <QTextStream>
int main()
{
QFile file("out.dat");
if (!file.open(QIODevice::WriteOnly))
return 1;
QDataStream out(&file);
out << "The magic number is: " << 49 << "\n";
}
Open QFile with WriteOnly flag
Foundations of Qt Development\Chapter08\fileexist\main.cpp
/*
* Copyright (c) 2006-2007, Johan Thelin
*
* All rights reserved.
*
* 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 APress 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.
*
*/
#include <QFile>
#include <QtDebug>
int main( int argc, char **argv )
{
QFile file( "testfile.txt" );
if( !file.exists() )
{
qDebug() << "The file" << file.fileName() << "does not exist.";
return 0;
}
if( !file.open( QIODevice::WriteOnly ) )
{
qDebug() << "Could not open" << file.fileName() << "for writing.";
return 0;
}
qDebug() << "The file opened.";
file.close();
return 0;
}
Open text file for write-operation
#include <QFile>
#include <QTextStream>
int main()
{
QFile file("out.txt");
if (!file.open(QIODevice::WriteOnly | QIODevice::Text))
return 1;
QTextStream out(&file);
out << "The magic number is: " << 49 << "\n";
}
Output with QFile
#include <QtCore>
#include <iostream>
#include <stdio.h>
using namespace std;
int main(int argc, char* argv[])
{
QFile in("c:\\a.txt");
if(!in.open(QIODevice::ReadOnly|QIODevice::Text)) {
cerr << "File " << argv[1] << " does not exist" << endl;
}
QFile out;
out.setFileName(argv[2]);
if (out.exists()) {
cerr << "File" << argv[2] << " already exists" << endl;
return 1;
}
if(!out.open(QIODevice::WriteOnly|QIODevice::Text)) {
cerr << "Failed to open file " << argv[2] << " for writing" << endl;
return 1;
}
while (!in.atEnd()) {
QByteArray line = in.readLine();
if (!line.trimmed().isEmpty() && !line.trimmed().startsWith("#"))
out.write(line);
}
in.close();
out.close();
return 0;
}
Read byte array from text file
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QFile>
#include <QTextStream>
static void process_line(const QByteArray &)
{
}
static void process_line(const QString &)
{
}
int main()
{
QFile file("in.txt");
if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
return 1;
while (!file.atEnd()) {
QByteArray line = file.readLine();
process_line(line);
}
}
Read file till file end
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QFile>
#include <QTextStream>
static void process_line(const QByteArray &)
{
}
static void process_line(const QString &)
{
}
int main()
{
QFile file("in.txt");
if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
return 1;
while (!file.atEnd()) {
QByteArray line = file.readLine();
process_line(line);
}
}
Read text file line by line
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QFile>
#include <QTextStream>
static void process_line(const QByteArray &)
{
}
static void process_line(const QString &)
{
}
int main()
{
QFile file("modules");
if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
return 1;
QTextStream in(&file);
QString line = in.readLine();
while (!line.isNull()) {
process_line(line);
line = in.readLine();
}
}