Qt program crash why?

Wasee

Hi everyone;
I code following and getting ASSERT: "count > 0" error. The program has unexpectedly finished. Why?

QProcess proc;
QStringList args;

proc.setProcessChannelMode(QProcess::MergedChannels);
args << "devmem2" << "0x80000000";

proc.start("sudo", args);
if(proc.waitForFinished())
{
    QString result = QString(proc.readAll());
    qDebug() << "devmem2 done and returning" << result;
    QString dds_en = result.mid(result.lastIndexOf("0x"));
    QString test=dds_en.simplified();
    qDebug()<<"Detected:"<<dds_en;
    if(test="0x0"){
    QProcess p1 ;
                    p1.startDetached("/bin/bash", QStringList() << "-c" << "/home/ijaz/bashScripts/script1.sh");
                    QProcess Rx_CF;
                    Rx_CF.start("cat /sys/bus/iio/devices/iio:device1/out_altvoltage0_RX_LO_frequency");
                    Rx_CF.waitForFinished(-1); // will wait forever until finished
                    Rx_CF_read =Rx_CF.readAllStandardOutput();
                     qDebug() << "RX LO"<<Rx_CF_read;
}
                 if(test="0x1"){
                 ac=Rx_CF_read;
                  QFile f("/sys/bus/iio/devices/iio:device1/out_altvoltage1_TX_LO_frequency");
                  if (f.open(QIODevice::WriteOnly))
                  {
                      qint64 count = f.write(ac.toUtf8());
                      Q_ASSERT(count > 0);
                      f.close();
                     qDebug()<<"QFile Run"<<count;
                  }
}

}
else
    qDebug() << "failled to start devmem2";

Thanks

KroMignon

This post is deleted!

Wasee

@KroMignon Hi;
Rx_CF_read and ac are define in header file as QString. Rx_CF_read is RX LO value which is reading from device continuously.
Thanks

jsulm

@Wasee said in Qt program crash why?:

Why?

Ask https://doc.qt.io/qt-5/qfiledevice.html#error

KroMignon

@Wasee said in Qt program crash why?:

Rx_CF_read and ac are define in header file as QString. Rx_CF_read is RX LO value which is reading from device continuously.
Thanks

@Wasee

Are you sure Rx_CF_read contains a valid value?
Why are you using an extra copy to ac?
Are you are writing into a linux virtual file, I don't think it supports UTF-8, but should be latin1.

I would change to code as follow, to understand what's happening:

    if(test=="0x1"){
        QFile f("/sys/bus/iio/devices/iio:device1/out_altvoltage1_TX_LO_frequency");
        qDebug() << "Try to set out_altvoltage1_TX_LO_frequency to" << Rx_CF_read;
        if (f.open(QIODevice::WriteOnly))
        {
            qint64 count = f.write(Rx_CF_read.toLatin1());
            Q_ASSERT(count > 0);
            f.close();
            qDebug()<<"QFile Run"<<count;
        }
    }

EDIT ==> = is to set a value, to compare use ==!!!!
if(test="0x0") ==> if(test=="0x0")
if(test="0x1") ==> if(test=="0x1")

Wasee

@KroMignon Hi;
I change the code but getting ASSERT: "count > 0" error. The program has unexpectedly finished.

Try to set out_altvoltage1_TX_LO_frequency to ""
Thanks

KroMignon

@Wasee said in Qt program crash why?:

Try to set out_altvoltage1_TX_LO_frequency to ""

According to the debug message, you are writing an empty string.
So why should count be greater than 0?

Have you also change the if statements?
if(test="0x1") will change test to "0x1" and not compare test with string "0x1"

In C/C++ the comparison operator is ==

Wasee

@KroMignon Hi;
If statement is working for if(test=="0x0") but not for if(test=="0x1"). Even test value in terminal is "0x1". at this point not entertaining to this if condition.
thanks

JonB

@Wasee
You really need to use a debugger, or even just debug statements, to find out for yourself things like what is in a variable, how should asking here help, other people don't know whether you get 0x0 versus 0x1 or whatever back, you are best placed to discover that....

KroMignon

@Wasee said in Qt program crash why?:

If statement is working for if(test=="0x0") but not for if(test=="0x1"). Even test value in terminal is "0x1". at this point not entertaining to this if condition.
thanks

I don't want to hurt you, but it looks like you are not really understanding what you are doing.
Why you don't use the debugger to set break points and running this part of code step by step to see what is really happening, as @JonB suggest to you?