The inferior stopped because it triggered an exception. Stopped in thread 0 by: Exception at 0x7ff9033da03a, code: 0xc0000005: read access violation at: 0x6c, flags=0x0 (first chance).

Tague Carlyon

Hello!

I am in need of some help. I am trying to get a label to periodically refresh every single second. However, when I try to create a private/public function to connect to a timer it crashes.

hud.h:

#ifndef HUD_H
#define HUD_H

#include <QWidget>
#include <QHBoxLayout>
#include <QVBoxLayout>
#include <QLabel>
#include <QTimer>
#include <qobject.h>

class Hud : public QWidget
{
Q_OBJECT

public:
Hud();

public slots:
void update();

private:
void updateText();

QHBoxLayout *hbox;
QVBoxLayout *vboxleft;
QVBoxLayout *vboxright;

QLabel *vertically;
QLabel *laid;
QLabel *out;
QLabel *text;

QLabel *verticallyright;
QLabel *laidright;
QLabel *outright;
QLabel *textright;

QTimer *timer;

int num = 1;

};

#endif // HUD_H

hud.cpp:

#include "hud.h"

Hud::Hud(){

// macro structure
/*QHBoxLayout *hbox = new QHBoxLayout(this);
QVBoxLayout *vboxleft = new QVBoxLayout();
QVBoxLayout *vboxright = new QVBoxLayout();



// left side text wall
QLabel *vertically = new QLabel();
vertically->setText("Vertically");
QLabel *laid = new QLabel();
laid->setText("Laid");
QLabel *out = new QLabel();
out->setText("Out");
QLabel *text = new QLabel();
text->setText("Text");

// right side text wall
QLabel *verticallyright = new QLabel();
verticallyright->setText("Vertically right");
QLabel *laidright = new QLabel(this);
laidright->setText("Laid");
QLabel *outright = new QLabel();
outright->setText("Out right");
QLabel *textright = new QLabel();
textright->setText("Text right");

// add text wall to left vbox
vboxleft->addWidget(vertically);
vboxleft->addWidget(laid);
vboxleft->addWidget(out);
vboxleft->addWidget(text);

// add text wall to right vbox
vboxright.addWidget(verticallyright);
vboxright.addWidget(laidright);
vboxright.addWidget(outright);
vboxright.addWidget(textright);

// add left and right vbox to master hbox
hbox->addLayout(vboxleft);
hbox->addLayout(vboxright);

//QTimer *timer = new QTimer(this);
//QObject::connect(timer, SIGNAL(timeout()), this, SLOT(update()));
//timer->start(1000);
updateText();*/

QLabel *textright = new QLabel(this);
textright->setText("text");

updateText();

};

void Hud::updateText(){

textright->setText(QString(num));

};

void Hud::update(){
updateText();
}

Main.cpp:

#include "hud.h"
#include <QApplication>

int main(int argc, char *argv[])
{
QApplication app(argc, argv);

Hud hud;
hud.resize(240, 230);
hud.setWindowTitle("hud");
hud.show();

return app.exec();

}

Thank you for your attention!

Tague Carlyon

It crashes at line:
textright->setText(QString(num));

mrjj

Hi
I think you hit a classic one.

QLabel *textright = new QLabel(this); <<< local variable you new
textright->setText("text");

void Hud::updateText(){
textright->setText(QString(num)); <<<< this variable is the one from .h . the member
};

so you do not new the member textright widget, but created a new local one instead.
(so the one in Hud .h is a dangling pointer )

so what you want is

textright = new QLabel(this); // new the member one.

Tague Carlyon

That fixed it. Thank you very much!