如何用QT实现文件的读写

    读文件    QFile file_r("/home/xmltest/data.txt");    if (!file_r.open(QIODevice::ReadOnly | QIODevice::Text))    {        qDebug("fail");    }    while (!file_r.atEnd())    {        QByteArray line = file_r.readLine();        qDebug()<<line;        readDate.append(QString(line));        listWidget->addItem(readDate.value(1));    }    file_r.close();    写文件    QStringList dateList;    dateList<<"gfsdj"            <<"sghfjs"            <<"s2222";    qDebug()<<dateList;    QFile file_w("/home/xmltest/data.txt");    if(!file_w.open(QIODevice::Append | QIODevice::Text))    {        qDebug("fail");    }    QTextStream tt(&file_w);    for(int i=0;i<3;i++)    {        tt<<dateList.value(i)<<endl;    }    file_w.close();
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C/C++ code
     QFile file("in.txt");     if (!file.open(QIODevice::ReadOnly | QIODevice::Text))         return;     QTextStream in(&file);     while (!in.atEnd()) {         QString line = in.readLine();         process_line(line);     }     QFile file("out.txt");     if (!file.open(QIODevice::WriteOnly | QIODevice::Text))         return;     QTextStream out(&file);     out << "The magic number is: " << 49 << "\n";