QProcess can read stderr but no stdout

[mastupristi]

I tried to use QProcess. I had some problems with reading stdout, so I create a simple project to reproduce the problem:

suppose to have a simple program like this:

#include<stdio.h>
#include <unistd.h>
 
int main(void)
{
    int o,e;
    o = e = 0;
 
    while(1)
    {
        printf("o %d\n", o);
        usleep(200000);
        fprintf(stderr,"e %d\n", e);
        usleep(200000);
 
        o++;
        e++;
    }
 
    return 0;
}

#include<stdio.h>
#include <unistd.h>

int main(void)
{
    int o,e;
    o = e = 0;

    while(1)
    {
        printf("o %d\n", o);
        usleep(200000);
        fprintf(stderr,"e %d\n", e);
        usleep(200000);

        o++;
        e++;
    }

    return 0;
}

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that works fine. When I run it I have the following output on the console:
o 0
e 0
o 1
e 1
o 2
e 2
o 3
e 3
o 4
e 4
o 5
...

then I have a simple qt project based on QProcess:

dialog.h:

#ifndef DIALOG_H
#define DIALOG_H
 
#include <QDialog>
#include <QProcess>
 
namespace Ui {
    class Dialog;
}
 
class Dialog : public QDialog
{
    Q_OBJECT
 
public:
    explicit Dialog(QWidget *parent = 0);
    ~Dialog();
 
private:
    Ui::Dialog *ui;
    QProcess extpro;
 
public slots:
    void btnpressed(void);
    void prtstdout(void);
    void prtstderr(void);
};
 
#endif // DIALOG_H

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>
#include <QProcess>

namespace Ui {
    class Dialog;
}

class Dialog : public QDialog
{
    Q_OBJECT

public:
    explicit Dialog(QWidget *parent = 0);
    ~Dialog();

private:
    Ui::Dialog *ui;
    QProcess extpro;

public slots:
    void btnpressed(void);
    void prtstdout(void);
    void prtstderr(void);
};

#endif // DIALOG_H

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and dialog.cpp:

#include "dialog.h"
#include "ui_dialog.h"
#include <QDebug>
 
Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
 
    connect(ui->pushButton,SIGNAL(clicked()),this, SLOT(btnpressed()));
 
    connect(&extpro, SIGNAL(readyReadStandardOutput()), this, SLOT(prtstdout()));
    connect(&extpro, SIGNAL(readyReadStandardError()), this, SLOT(prtstderr()));
}
 
Dialog::~Dialog()
{
    delete ui;
    extpro.kill();
}
 
 
void Dialog::btnpressed(void)
{
    extpro.start("../zozzo-build-desktop/zozzo");
}
 
void Dialog::prtstdout(void)
{
    qDebug() << QString(extpro.readAllStandardOutput());
}
 
void Dialog::prtstderr(void)
{
    qDebug() << QString(extpro.readAllStandardError());
}

#include "dialog.h"
#include "ui_dialog.h"
#include <QDebug>

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);

    connect(ui->pushButton,SIGNAL(clicked()),this, SLOT(btnpressed()));

    connect(&extpro, SIGNAL(readyReadStandardOutput()), this, SLOT(prtstdout()));
    connect(&extpro, SIGNAL(readyReadStandardError()), this, SLOT(prtstderr()));
}

Dialog::~Dialog()
{
    delete ui;
    extpro.kill();
}


void Dialog::btnpressed(void)
{
    extpro.start("../zozzo-build-desktop/zozzo");
}

void Dialog::prtstdout(void)
{
    qDebug() << QString(extpro.readAllStandardOutput());
}

void Dialog::prtstderr(void)
{
    qDebug() << QString(extpro.readAllStandardError());
}

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If I try to execute obtain only:
"e 0
"
"e 1
"
"e 2
"
"e 3
"
"e 4
"
"e 5
"
"e 6
"
"e 7
"

I can see only stderr. How can I have also stdout to have an output just like console?

In attachment there is the projects

thanks

[tbscope]

I haven't looked at all your code but are you sure that

printf("o %d\n", o);

printf("o %d\n", o);

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prints to stdout and not the current console/shell/...?

[mastupristi]

I haven't looked at all your code but are you sure that

printf("o %d\n", o);

printf("o %d\n", o);

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prints to stdout and not the current console/shell/...?

of course
anyway try to change that line to:

fprintf(stdout,"o %d\n", o);

fprintf(stdout,"o %d\n", o);

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thanks

[mastupristi]

of course
anyway try to change that line to:

fprintf(stdout,"o %d\n", o);

fprintf(stdout,"o %d\n", o);

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I have just tried
Same behaviour