Get result from external c++ program

Question

I installed Qt creator 5.15 in my ubuntu18.

I checked documentation how to plot graphics in C++ on Qtcreator and would like to get data from external test c++ program called "test" with Qprocess.

Here is a simple main.cpp:

#include <iostream>
#include <iostream>
#include "ZFraction.h"

using namespace std;

int main()
{
    ZFraction a(4,5);      
    ZFraction b(2);        
    ZFraction c,d;         

   c = a+b;              
   d = a*b;               

    cout << a << " + " << b << " = " << c << endl;

    cout << a << " * " << b << " = " << d << endl;

    return 0;
}

Here is my Qt creator program:

#include "mafenetre.h"
#include "ui_mafenetre.h"

//using namespace QtCharts;

const quint64 start=QDateTime::currentSecsSinceEpoch();
const int limiteRandom=2;


Mafenetre::Mafenetre(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Mafenetre)
{
    ui->setupUi(this);
    myprocess = new QProcess(this);
    

    QString program = ("./test");
    arguments << " ";

    myprocess->start(program, arguments);
    //myprocess->waitForReadyRead();

    connect(monTimer,SIGNAL(timeout()),this,SLOT(refresh_graph()));
    connect(myprocess,SIGNAL(readyReadStandardOutput()),this,SLOT(readyReadStandardOutput()));
    connect(myprocess,SIGNAL(readyReadStandardError()),this,SLOT(readyReadStandardError()));
}

void Mafenetre::readyReadStandardOutput(){
    qDebug()<< myprocess->readAllStandardOutput();
 
}

void Mafenetre::readyReadStandardError(){
    qDebug() << myprocess->readAllStandardError();
}

Mafenetre::~Mafenetre()
{
    delete ui;
}

My question is from the c++ program, how can you get result of "d" or "c" variables as input of Qtcreator program ?

Answer 1

You must start the program after connecting.

#include "mafenetre.h"
#include "ui_mafenetre.h"

//using namespace QtCharts;

const quint64 start=QDateTime::currentSecsSinceEpoch();
const int limiteRandom=2;


Mafenetre::Mafenetre(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Mafenetre)
{
    ui->setupUi(this);
    myprocess = new QProcess(this);
    

    QString program = ("./test");
    arguments << " ";
    connect(myprocess,SIGNAL(readyReadStandardOutput()),this,SLOT(readyReadStandardOutput()));
    connect(myprocess,SIGNAL(readyReadStandardError()),this,SLOT(readyReadStandardError()));

    myprocess->start(program, arguments);
    //myprocess->waitForReadyRead();

    connect(monTimer,SIGNAL(timeout()),this,SLOT(refresh_graph()));
   
}

void Mafenetre::readyReadStandardOutput(){
    qDebug()<< myprocess->readAllStandardOutput();
 
}

void Mafenetre::readyReadStandardError(){
    qDebug() << myprocess->readAllStandardError();
}

Mafenetre::~Mafenetre()
{
    delete ui;
}