COM+QCustomPlot problem is QStringList[].toDouble()

banhmisua

hi. i am a newbie in QT. I need ur help to solve my problem.
my problem is : i can't read value of "giatri" when i use systax: giatri=QString(bufferSplit[0]).toDouble();
i still read bufferSpilt[0].
here my code:
void MainWindow::serialport_read()
{

QStringList bufferSplit = data_string.split("\n");
if(bufferSplit.length()<2)
{
    buffer=serialPort->readAll();
    data_string+=QString::fromStdString(buffer.toStdString());
}
else
{
    ui->pteReceive->insertPlainText(bufferSplit[0]);
    // show data read ok! eg: 96,80,94

    giatri=QString(bufferSplit[0]).toDouble();// not working
    //giatri++;
    time=time+1;
    addPoint(time,giatri);
    plot();
    data_string="";
}

}
and my result :

thank ur help!

jsulm

@banhmisua said in COM+QCustomPlot problem is QStringList[].toDouble():

my problem is : i can't read value of "giatri" when i use systax: giatri=QString(bufferSplit[0]).toDouble();
i still read bufferSpilt[0].

Can you please explain better?
Of course you read bufferSpilt[0] - because that is what you wrote!
So, what do you want to do?

banhmisua

i read data from my COM and i save it in QStringList bufferSplit[0] and i plot it by using QCustomPlot.
so i want convert bufferSplit[0] to double giatri and plot it. that's all.
thank u.

Christian Ehrlicher

@banhmisua said in COM+QCustomPlot problem is QStringList[].toDouble():

so i want convert bufferSplit[0] to double giatri and plot it. that's all.

But you do it already...

giatri=QString(bufferSplit[0]).toDouble()

What's the content of bufferSplit[0] ? Please add

qDebug() << "bufferSplit[0]:" << bufferSplit[0]

and post it here.

banhmisua

@Christian-Ehrlicher . i did as u said. and i have problem.
When i DEBUG step by step, everything is right!
bufferSplit[0]: "82"
bufferSplit[0]: "82"
bufferSplit[0]: "82"
bufferSplit[0]: "82"
bufferSplit[0]: "240"
bufferSplit[0]: "82"

but when i RUN. i got:

bufferSplit[0]: "82"
bufferSplit[0]: "\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u000082"
bufferSplit[0]: "\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u000082"
bufferSplit[0]: "\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u000082"
So what is problem here? can u tell me how solve it?
thank u very much.

Christian Ehrlicher

I don't see a problem here except that sometimes you get 0 as value which you have to handle. We don't know what 0 means in your context.