Qt写入txt文件

void MainWindow::on_pushButton_clicked()

{

    QDateTime da_time;

    QString time_str=da_time.currentDateTime().toString("yyyy-MM-dd HH-mm-ss");

    QString runPath = QCoreApplication::applicationFilePath();

    ui->label->setText(runPath);

    QDir *TEST = new QDir;

    bool exist = TEST->exists("TEST");

    if(!exist)

          bool ok = TEST->mkdir("TEST");

   QString fileName = "TEST/1.txt";

   QString str="0000000nnnnnnnnnnnnnnnn";

   QFile file(fileName);

   if(!file.open(QIODevice::WriteOnly  | QIODevice::Text|QIODevice::Append))

   {

      QMessageBox::warning(this,"sdf","can't open",QMessageBox::Yes);

   }

   QTextStream in(&file);

   in<<time_str+":"+str<<"\n";

   file.close();

}