Question

When I try to emit readAllStandardOutput() to a QString im getting an unexpected program crash, even if i connvert the QByteStream to a QString, any idea why that is? heres teh source

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QProcess>
#include <QString>


#include "exeprocess.h"

/*main window ---------------------------------------*/

namespace Ui {
    class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    QProcess *proc;

signals:
    void outLog(QString outLogVar); //plug this into the QTextEdit box

public slots:
    void logReady(); // plug the QProcess into this


private:
    Ui::MainWindow *ui;
};




#endif // MAINWINDOW_H

mainwindow.cpp

#include <QByteArray>

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QProcess *proc = new QProcess; //initialize proc
    QStringList arguments;
    arguments << "-h";

    connect(proc, SIGNAL(readyReadStandardOutput ()), this, SLOT(logReady()));

    proc->start("/Applications/Graphics/3Delight-9.0.87/bin/renderdl", arguments);

}

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

void MainWindow::logReady(){
    QString str = proc->readAllStandardOutput();
    emit outLog(str);
}

Thanks!

Answer 1

This line is the problem:

QProcess *proc = new QProcess; //initialize proc

You’re shadowing the member variable by reusing that name. When logReady is called, the ‘proc’ that you call readAllStandardOutput() on is a different (null) pointer and so everything crashes. The fix is simple: replace the above line with

proc = new QProcess;