源代码:
t7/lcdrange.h Example File
/****************************************************************
**
** Definition of LCDRange class, Qt tutorial 7
**
****************************************************************/
#ifndef LCDRANGE_H
#define LCDRANGE_H
#include <qvbox.h>
class QSlider;
class LCDRange : public QVBox
{
Q_OBJECT
public:
LCDRange( QWidget *parent=0, const char *name=0 );
int value() const;
public slots:
void setValue( int );
signals:
void valueChanged( int );
private:
QSlider *slider;
};
#endif // LCDRANGE_H
t7/lcdrange.cpp Example File
/****************************************************************
**
** Implementation of LCDRange class, Qt tutorial 7
**
****************************************************************/
#include "lcdrange.h"
#include <qslider.h>
#include <qlcdnumber.h>
LCDRange::LCDRange( QWidget *parent, const char *name )
: QVBox( parent, name )
{
QLCDNumber *lcd = new QLCDNumber( 2, this, "lcd" );
slider = new QSlider( Horizontal, this, "slider" );
slider->setRange( 0, 99 );
slider->setValue( 0 );
connect( slider, SIGNAL(valueChanged(int)),
lcd, SLOT(display(int)) );
connect( slider, SIGNAL(valueChanged(int)),
SIGNAL(valueChanged(int)) );
}
int LCDRange::value() const
{
return slider->value();
}
void LCDRange::setValue( int value )
{
slider->setValue( value );
}
t7/main.cpp Example File
/****************************************************************
**
** Qt tutorial 7
**
****************************************************************/
#include <qapplication.h>
#include <qpushbutton.h>
#include <qlcdnumber.h>
#include <qfont.h>
#include <qvbox.h>
#include <qgrid.h>
#include "lcdrange.h"
class MyWidget : public QVBox
{
public:
MyWidget( QWidget *parent=0, const char *name=0 );
};
MyWidget::MyWidget( QWidget *parent, const char *name )
: QVBox( parent, name )
{
QPushButton *quit = new QPushButton( "Quit", this, "quit" );
quit->setFont( QFont( "Times", 18, QFont::Bold ) );
connect( quit, SIGNAL(clicked()), qApp, SLOT(quit()) );
QGrid *grid = new QGrid( 4, this );
LCDRange *previous = 0;
for( int r = 0 ; r < 4 ; r++ ) {
for( int c = 0 ; c < 4 ; c++ ) {
LCDRange* lr = new LCDRange( grid );
if ( previous )
connect( lr, SIGNAL(valueChanged(int)),
previous, SLOT(setValue(int)) );
previous = lr;
}
}
}
int main( int argc, char **argv )
{
QApplication a( argc, argv );
MyWidget w;
a.setMainWidget( &w );
w.show();
return a.exec();
}
按了第二个LCDRange控件之后就退出,同时显示
segmentation fault.
用gdb调试,错误出现在
void LCDRange::setValue( int value )
{
slider->setValue( value );
}
中的slider->setValue(value);
但我不知道为什么会这样,求教高手。
[ 此贴被XChinux在2006-05-28 08:17重新编辑 ]