Question

bool QDomDocument::setContent ( const QByteArray & data, bool namespaceProcessing, QString * errorMsg = 0, int * errorLine = 0, int * errorColumn = 0 )

this function’s first parameter is const QByteArray & data,then,following:

void LoadData(QString& str)
{
    QString strPath = str;
    strPath += "/contact.xml";
    QFile file(strPath);
    if(!file.open(QIODevice::ReadOnly)) 
    {
        return;
    }
    QDomDocument doc;
    if(!doc.setContent(&file))
    {
        file.close();
        return;
    }
    file.close();
    ...
}

Top code can work in my project but it was not created by me.I can’t understand &file,
what do you guys think about this question?

Answer 1

The are multiple versions of QDomDocument::setContent. The above code is using:

bool QDomDocument::setContent( 
    QIODevice * dev, 
    QString * errorMsg = 0, 
    int * errorLine = 0,
    int * errorColumn = 0 
)

since QFile inherits QIODevice and &file returns a pointer to a QFile.