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

[brian777754]

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.

[brian777754]

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

[VRonin]

https://doc.qt.io/qt-5/qprocess.html#communicating-via-channels

[brian777754]

@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.

[VRonin]

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;
}

[brian777754]

@VRonin thank you so much