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/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the either Technology Preview License Agreement or the
** Beta Release License Agreement.
**
** 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 1.0, 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 are unsure which license is appropriate for your use, please
** contact the sales department at http://qt.nokia.com/contact.
** $QT_END_LICENSE$
**
****************************************************************************/
//! [0]
QDataStream out(...);
QVariant v(123); // The variant now contains an int
int x = v.toInt(); // x = 123
out << v; // Writes a type tag and an int to out
v = QVariant("hello"); // The variant now contains a QByteArray
v = QVariant(tr("hello")); // The variant now contains a QString
int y = v.toInt(); // y = 0 since v cannot be converted to an int
QString s = v.toString(); // s = tr("hello") (see QObject::tr())
out << v; // Writes a type tag and a QString to out
...
QDataStream in(...); // (opening the previously written stream)
in >> v; // Reads an Int variant
int z = v.toInt(); // z = 123
qDebug("Type is %s", // prints "Type is int"
v.typeName());
v = v.toInt() + 100; // The variant now hold the value 223
v = QVariant(QStringList());
//! [0]
//! [1]
QVariant x, y(QString()), z(QString(""));
x.convert(QVariant::Int);
// x.isNull() == true
// y.isNull() == true, z.isNull() == false
// y.isEmpty() == true, z.isEmpty() == true
//! [1]
//! [2]
QVariant variant;
...
QColor color = variant.value<QColor>();
//! [2]
//! [3]
QColor color = palette().background().color();
QVariant variant = color;
//! [3]
//! [4]
QVariant v;
v.setValue(5);
int i = v.toInt(); // i is now 5
QString s = v.toString() // s is now "5"
MyCustomStruct c;
v.setValue(c);
...
MyCustomStruct c2 = v.value<MyCustomStruct>();
//! [4]
//! [5]
QVariant v;
MyCustomStruct c;
if (v.canConvert<MyCustomStruct>())
c = v.value<MyCustomStruct>(v);
v = 7;
int i = v.value<int>(); // same as v.toInt()
QString s = v.value<QString>(); // same as v.toString(), s is now "7"
MyCustomStruct c2 = v.value<MyCustomStruct>(); // conversion failed, c2 is empty
//! [5]
//! [6]
QVariant v = 42;
v.canConvert<int>(); // returns true
v.canConvert<QString>(); // returns true
MyCustomStruct s;
v.setValue(s);
v.canConvert<int>(); // returns false
v.canConvert<MyCustomStruct>(); // returns true
//! [6]
//! [7]
MyCustomStruct s;
return QVariant::fromValue(s);
//! [7]
//! [8]
QObject *object = getObjectFromSomewhere();
QVariant data = qVariantFromValue(object);
//! [8]
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