QDataSteam.

[wookoon]

I want write a class which is inherit from QObject to the file with QDataStream, so I overload operator << and operator >>.

Class C : public QObject
{
    Q_OBJECT
    ......
    friend QDataStream & operator << (QDataStream &dataStream, C &c);
    friend QDataStream & operator >> (QDataStream &dataStream, C &C);
    .......
}
 
.................
QDataStream & operator << (QDataStream &dataStream, C &c)
{
 
}
 
QDataStream & operator >> (QDataStream &dataStream, C &c)
{
 
}

Class C : public QObject
{
    Q_OBJECT
    ......
    friend QDataStream & operator << (QDataStream &dataStream, C &c);
    friend QDataStream & operator >> (QDataStream &dataStream, C &C);
    .......
}

.................
QDataStream & operator << (QDataStream &dataStream, C &c)
{

}

QDataStream & operator >> (QDataStream &dataStream, C &c)
{

}

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but it can't compile success.The error is:multiple definition of "operator" <<(QDataStream&,C&)
multiple definition of "operator" >>(QDataStream&,C&)

if this class is not inherit from the QObject and delete macro Q_OBJECT, then it will compile success. So What's the problem....?