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how to pass a double value from c++ to a qt user interface



  • I have made a user interface using qt creator 5.9.1. I want to be able to connect it now to an external c++ program so that I can update the values of the double spinboxes. Could someone show a simple example of what code I would need to write to send the double value from the external c++ program. And what code I would need to write to receive that value in the qt program.



  • I mean a c++ program that is not on qt. I am using ubunto 16.04





  • @VRonin could you give me a simple example of how to actually implement this to pass a double value in from c++ to qt I have read this but I am still confused by it.



  • Should be something like:

    OtherProgram

    #include <iostream>
    int main(){
    double aNumber;
    std::cin >> aNumber;
    std::cout << "Doubled number: " << 2.0*aNumber;
    return 0;
    }
    

    QtProgram

    #include <QCoreApplication> 
    #include <QProcess>
    #include <QByteArray>
    #include <QDebug>
    int main(int argc, char **argv)
    {
    const double magicNumber = 1.56;
    QCoreApplication app(argc,argv);
    QProcess otherProcess;
    otherProcess.start("OtherProgram.exe");
    if (!otherProcess.waitForStarted())
            return 1;
    otherProcess.write(QByteArray::number(magicNumber,'f'));
    if (!otherProcess.waitForReadyRead())
            return 1;
    qDebug() << otherProcess.readAllStandardOutput();
    if (!otherProcess.waitForFinished())
            return 1;
    return 0;
    }
    


  • @VRonin thank you so much


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