Unexplained Crash

[jbkc85]

Hi all, I am fairly new at QT and have downloaded the new SDK and have the latest QT libraries (which i believe is 4.5?). I wanted to make a quick widget to allow me to run a test program, showing simple LCD and displays, however whenever I run it the QT program crashes on me, with no error codes. Anyway, here is the code...

************************************************** **************

//#include <QtCore/QCoreApplication>

#include <QApplication>
#include <QLCDNumber>
#include <QPushButton>
#include <QWidget>
#include <QVBoxLayout>
#include <QPushButton>

#include "digitalclock.h"
#include <stdlib.h>
#include <stdio.h>

#define userMinTemp 15

char display[10];
int newTemp = 0;

/* Widget Class Creator */
class MyWidget : public QWidget
{
public:
MyWidget(QWidget *parent = 0);

public slots:
void MyWidget::newTempMain();
};
MyWidget::MyWidget(QWidget *parent) : QWidget(parent)
{
QPushButton *quit = new QPushButton(tr("Quit"));
quit->setFont(QFont("Times", 12, QFont::Bold));

QLCDNumber *lcd = new QLCDNumber(newTemp);
lcd->setSegmentStyle(QLCDNumber::Filled);

QPushButton *devDisplay = new QPushButton(display);
devDisplay->setFont(QFont("Times",18,QFont::Bold));

//DigitalClock clock;

// Quit when clicked Quits...
connect(quit, SIGNAL(clicked()), qApp, SLOT(quit()));
// devDisplay when clicked creates a new temp and says whether or not ac/heat
connect(devDisplay, SIGNAL(clicked()), this, SLOT(newTemp()));

QVBoxLayout *layout = new QVBoxLayout;
layout->addWidget(devDisplay);
layout->addWidget(lcd);
layout->addWidget(quit);
//layout->addWidget(clock);
setLayout(layout);

}

void MyWidget::newTempMain()
{
newTemp = (rand()%101);

if( newTemp <= userMinTemp )
{
strncpy("Heat", display, sizeof(display));
//display = "Heat";
}
else
{
strncpy("AC", display, sizeof(display));
//display = "AC";
}
}

void newTempMain()
{
newTemp = (rand()%101);

if( newTemp <= userMinTemp )
{
strncpy("Heat", display, sizeof(display));
//display = "Heat";
}
else
{
strncpy("AC", display, sizeof(display));
//display = "AC";
}
}

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

QApplication app(argc, argv);
MyWidget widget;
widget.show();
return app.exec();
}

************************************************** ***************

If there are any suggestions or anything that anyone sees out of the ordinary or that causes potential crashing, please let me know...its buggin the living hell outta me.

Thanks!

[spirit]

first of all you need to add Q_OBJECT marco right here

class MyWidget : public QWidget
{
    Q_OBJECT
...

class MyWidget : public QWidget
{
    Q_OBJECT
...

To copy to clipboard, switch view to plain text mode 

if you don't do this then signal/slot mechanism will not work.

then there is no needed to use strncpy, QString already has all what you need for working with strings.

are these variables quit, lcd & devDisplay declared as class member, ?
if not then this can cause a crash, because in ctor you have initialized local variables.

PS. use tag code please.