如何重用QFile？

Question

我想用下面的代码保存两个文件的目录：

QString dir = QFileDialog::getExistingDirectory(this, tr("Open Directory"),QDesktopServices::storageLocation(QDesktopServices::DesktopLocation), 
             QFileDialog::ShowDirsOnly 
             | QFileDialog::DontResolveSymlinks); 
QFile file(dir.append("/GlobalMessage.txt")); 
if(file.open(QIODevice::WriteOnly | QIODevice::Text)){ 
    QTextStream out(&file); 

    for (int i=0;i<t_global.size();i++){ 
     out << t_global[i]<<" "<<y_lat.y[i]<<" "<<y_lng.y[i]<<" "<<y_alt.y[i]<<" "<<y_vx.y[i]<<" "<<y_vy.y[i]<<" "<<y_vz.y[i]<<"\n"; 
    } 
} 
// optional, as QFile destructor will already do it: 
file.close(); 

file.setFileName(dir.append("/AttitudeMessage.txt")); 
if(file.open(QIODevice::WriteOnly | QIODevice::Text)){ 
    QTextStream out(&file); 

    for (int i=0;i<t_attitude.size();i++){ 
     out << t_attitude[i]<<" "<<y_roll.y[i]<<" "<<y_pitch.y[i]<<" "<<y_yaw.y[i]<<"\n"; 
    } 
} 
file.close(); 

然而Seconde系列file.open（）总是fail.What是重用此文件对象的正确方法？

Answer 1

append更改底层QString。

这是file.filename()在你的程序的输出：

"/tmp/GlobalMessage.txt" 
"/tmp/GlobalMessage.txt/AttitudeMessage.txt" 

只需使用

QFile file(dir + "/GlobalMessage.txt"); 

和

file.setFileName(dir + "/AttitudeMessage.txt"); 

Answer 2

这可能是你生成路径的问题，因为此代码实际上适用于我：

QFile file("d:\\a.txt"); 
if (file.open(QIODevice::ReadOnly | QIODevice::Text)) { 
    qDebug() << file.readAll(); 

    file.close(); 

    file.setFileName("d:\\b.txt"); 
    if (file.open(QIODevice::ReadOnly | QIODevice::Text)) { 
     qDebug() << file.readAll(); 
    } 
} 

编辑：是的，西蒙先发现了它，你太多了。