QVaraint类

QDataStream out(...);
QVariant v(123);    // The variant now contains an int
int x = v.toInt();   // 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());你甚至可以存储QList<QVariant>和QMap<QString ,QVariant>.