#include <QApplication>
#include <QtGui>
#include "ui_interface.h"
#include <iostream>
using namespace std;

class FechaApp {
    public:

    void fechar(char  elemento){ // da erro aqui
     QObject::connect(elemento, SIGNAL(clicked()), QApplication, SLOT(quit()));
    }


}

int main(int argc, char *argv[]) {
QApplication app(argc, argv);
QMainWindow *widget = new QMainWindow();

Ui::MainWindow form;

form.setupUi(widget);
//form.setupUi();

Fechar x;
x.fechar(form.pushButton);
//QObject::connect(form.pushButton, SIGNAL(clicked()), &app, SLOT(quit()));

widget->show();

return app.exec();
}