qt specific implementation - qt

Question

I have this snippet of the code:
#include <QApplication>
#include <QFont>
#include <QLCDNumber>
#include <QPushButton>
#include <QSlider>
#include <QVBoxLayout>
#include <QWidget>
class MyWidget : public QWidget
{
public:
MyWidget(QWidget *parent = 0);
};
MyWidget::MyWidget(QWidget *parent)
: QWidget(parent)
{
QPushButton *quit = new QPushButton(tr("Quit"));
quit->setFont(QFont("Times", 18, QFont::Bold));
QLCDNumber *lcd = new QLCDNumber(3);
lcd->setSegmentStyle(QLCDNumber::Flat);
QSlider *slider = new QSlider(Qt::Horizontal);
slider->setRange(0, 999);
slider->setValue(0);
connect(quit, SIGNAL(clicked()), qApp, SLOT(quit()));
connect(slider, SIGNAL(valueChanged(int)),
lcd, SLOT(display(int)))
QVBoxLayout *layout = new QVBoxLayout;
layout->addWidget(quit);
layout->addWidget(lcd);
layout->addWidget(slider);
setLayout(layout);
}
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
MyWidget widget;
widget.show();
return app.exec();
}
when I reach the max of the interval, I want to quit, how can I implement this with signals and slots, thanks in advance

Answer 1

Add one more slot-function to your MyWidget class, for example on_maximum_exit(int) like that:
class MyWidget : public QWidget
{
public:
MyWidget(QWidget *parent = 0);
public slots:
void on_maximum_exit(int );
};
Define new function:
void MyWidget::on_maximum_exit(int value)
{
if (value == slider->maximum())
close();
}
In MyWidget consctuctor, after connect(slider, SIGNAL(valueChanged(int)),... add:
/* ... */
connect(slider, SIGNAL(valueChanged(int)), this, SLOT(on_maximum_exit(int)));
/* ... */
And of course use Qt docs!

Answer 2

Like I said in the other post this should work for you:
main.cpp
#include <QApplication>
#include "mywidget.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
MyWidget widget;
widget.show();
return app.exec();
}
mywidget.h
#ifndef MYWIDGET_H
#define MYWIDGET_H
#include <QWidget>
#include <QObject>
include <QPushButton>
#include <QSlider>
class MyWidget : public QWidget
{
Q_OBJECT
public:
MyWidget(QWidget *parent = 0);
~MyWidget(){};
public slots:
void getSliderValueAndQuit();
private:
QPushButton *quit;
QSlider *slider;
};
#endif // MYWIDGET_H
myWidget.cpp
#include "mywidget.h"
#include <QWidget>
#include <QObject>
#include <QApplication>
#include <QFont>
#include <QLCDNumber>
#include <QPushButton>
#include <QSlider>
#include <QVBoxLayout>
MyWidget::MyWidget(QWidget *parent) :
QWidget(parent)
{
quit = new QPushButton(tr("Quit"));
quit->setFont(QFont("Times", 18, QFont::Bold));
QLCDNumber *lcd = new QLCDNumber(3);
lcd->setSegmentStyle(QLCDNumber::Flat);
slider = new QSlider(Qt::Horizontal);
slider->setRange(0, 999);
slider->setValue(0);
connect(quit, SIGNAL(clicked()), qApp, SLOT(quit()));
connect(slider, SIGNAL(valueChanged(int)),lcd, SLOT(display(int)));
connect(slider,SIGNAL(sliderReleased()), SLOT(getSliderValueAndQuit()));
QVBoxLayout *layout = new QVBoxLayout;
layout->addWidget(quit);
layout->addWidget(lcd);
layout->addWidget(slider);
setLayout(layout);
}
void MyWidget::getSliderValueAndQuit(){
if(slider->value() == slider->maximum())
close();
}