reading from Serial port and writing data to a file

Muzab

I find it strange. I can read from the serial port and I can see that data is read in the application output window. There is no error, meaning it is writing to the file, But when I check the file, there is nothing in it. Can someone suggest me why this is happening ? thanks!

void MainWindow::readSerial()
{
QStringList buffer_split = serialBuffer.split(";");

if(buffer_split.length()<4)
{
    serialData = Board->readAll();
    serialBuffer = serialBuffer + QString::fromStdString(serialData.toStdString());
    serialData.clear();
}
else
{
    serialBuffer = "";
    qDebug() <<QDateTime::currentDateTime().toString("hh:mm:ss.zzz")<<endl;
    qDebug() <<"Buffer Split ="<<buffer_split<<endl;  
    sensor_Value= (buffer_split[0]).toDouble();;       
    qDebug() <<"Sensor Value= "<<sensor_Value<<endl;

/* Write buffer to the file */
QFile file("data.txt");
QString input;
QTextStream stream (&file);
input = sensor_Value;
while(file.open(QIODevice::WriteOnly|QIODevice::Text|QIODevice::Append))
{
stream<<input;
}
file.close();
}
}

SGaist

Hi,

The correct flow for QTextStream is rather:

QFile data("data.txt");
if (data.open(QFile::WriteOnly | QFile::Truncate)) {
    QTextStream out(&data);
    out << sensor_Value;
} else {
    qDebug() << "Failed to open file" << data.error();
}

On a side note, why not just do serialData += Board->readAll(); ? You're doing multiple useless conversions.

[edit: Fixed code SGaist]

kshegunov

@Muzab said:

here is no error, meaning it is writing to the file

To add to @SGaist, how do you know there's no error when no checks against the stream's status flag are made?

Muzab

The code that I am using to write to a file works if i run it independently and it won't when I use it in my project file.
Thanks for the corrections.

qDebug() << "Failed to open file" << data.error(); // seems to be correct instead of data->error()

The problem was with

QString input;

It was getting reinitialized each time. Sorry ! dudes.. for the blunder! I truly appreciate your kind response.