Console app in Qt with a QCoreApplication (just a personal note...)

main.cpp

#include <QCoreApplication>
#include <worker.h>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    Worker *w = new Worker(&a);

    QObject::connect(w, SIGNAL(finished()), &a, SLOT(quit()));
    QTimer::singleShot(0, w, SLOT(run()));    // launch it

    return a.exec();
}

// worker.cpp 

#include <QtCore>
#include <QString>
#include <worker.h>
#include <memory>

void Worker::run() {
    printf("Hello world...\n\n");
    emit finished();
}

// worker.h

#ifndef WORKER_H
#define WORKER_H

#include <QtCore>

class Worker : public QObject {
    Q_OBJECT

    public:
        Worker(QObject *parent = 0) : QObject(parent) {}
    public slots:
        void run();
    signals:
        void finished();
};

#endif // WORKER_H