C program for getting Linux system information

In most of the Linux systems we use the command “uname” to print the system information in the terminal.

Ex:

           $uname -a

which gives the information about the system such as OS name, kernel version, release,domain name etc... Similerly we can get that information through C Programming.

Now I will let you how to print Linux system information through C programming in Linux, by using the structure “struct utsname”, and the system call uname() which return 0 on success, -1 on error.. See the code snnippet given below...

uname.c:

#include<stdio.h>

#include<sys/utsname.h>

QGraphicsView Example Program by inheriting QGraphicsView class

In the prevoius qgraphicsview example we created the view (QgraphicsView) and placed the scene in this view.Now in this example we created a class and inherit this class from QGraphicsView class, so the class being inherited acts like view and we will set the scene for this inherited class.

Check the example program and the output below...

• graphics.h

#ifndef GRAPHICS_H
#define GRAPHICS_H
#include <QtGui/QWidget>
#include <QGraphicsEllipseItem>
#include <QGraphicsScene>
#include <QGraphicsView>
class graphics : public QGraphicsView
{
    Q_OBJECT
    QGraphicsScene *scene;
    QGraphicsEllipseItem *itm_ellipse;
    QGraphicsTextItem *itm_txt;
    QGraphicsLineItem *itm_line;
    QGraphicsPolygonItem *itm_poly;
    
public:
    graphics(QWidget *parent = 0);
    ~graphics();
};
#endif // GRAPHICS_H

QgraphicsView simple example program

Here is a simple QgraphicsView example program in Qt.

In this example we created a scene (QGraphicsScene) and placed all the items  in this scene by specifying the scene object while creating the graphics item.Andat last we created the view (QGraphicsView) and scene is placed in this view by using setScene() method of QgraphicsView.

#include <QtGui/QApplication>

#include<QGraphicsView>

#include<QGraphicsScene>

#include<QGraphicsSimpleTextItem>

#include<QGraphicsRectItem>

#include<QGraphicsEllipseItem>

#include<QVector>

#include<QGraphicsPolygonItem>

int main( int argc, char **argv )

{

    QApplication app( argc, argv );

    QGraphicsScene scene( QRect( -100, -100, 400, 400 ) );

    scene.setBackgroundBrush(Qt::cyan);

    QGraphicsSimpleTextItem *textItem = new QGraphicsSimpleTextItem(

                "technoyouth10", 0, &scene );

    textItem->setPos( -50, -50 );

    textItem->setFlag(QGraphicsItem::ItemIsMovable);

    QGraphicsRectItem *rectItem = new QGraphicsRectItem(

                QRect( 0, -0, 200, 40 ), 0, &scene );

    rectItem->setPen( QPen( Qt::red, 3, Qt::DashDotLine ) );

    rectItem->setBrush( Qt::green );

    QGraphicsEllipseItem *ellipseItem = new QGraphicsEllipseItem(

                QRect( 80, -80, 100, 75 ),

                0, &scene );

    ellipseItem->setPen( QPen(Qt::yellow) );

    ellipseItem->setBrush( Qt::magenta );

    QVector<QPointF> points;

    points << QPointF( 20, 50 ) << QPointF( 80, 50 ) << QPointF( 110, 80 )

           << QPointF( 50, 130 )<< QPointF( -10, 80 ) ;

    QGraphicsPolygonItem *polygonItem = new QGraphicsPolygonItem(

                QPolygonF( points ), 0, &scene );

    polygonItem->setPen( QPen(Qt::red) );

    polygonItem->setBrush( Qt::yellow );

    QGraphicsView view;

    view.setScene( &scene );

    view.show();

    return app.exec();

}

Output:

Run the program by pressing Ctrl+r...