#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QtNetwork/QNetworkReply>

namespace Ui {
    class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
private slots:
   void  saveimg(QNetworkReply*);
};

#endif // MAINWINDOW_H

#include <QtGui/QApplication>
#include "mainwindow.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QtNetwork/QNetworkAccessManager>
#include <QtNetwork/QNetworkRequest>
#include <QFile>
#include <QByteArray>
#include <QIODevice>
#include <QMessageBox>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QNetworkRequest req;
    QUrl url("http://www.openbsd.org/art/puffy/ppuf1000X907.gif");
    req.setUrl(url);
    QNetworkAccessManager *manager= new QNetworkAccessManager;
    manager->get(req);
    QObject::connect(manager, SIGNAL(finished(QNetworkReply*)), this, SLOT(saveimg(QNetworkReply*)));
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::saveimg(QNetworkReply *rep)
{
QString data = rep->readAll();

QFile file("C:\\images\\img.gif");
file.open(QIODevice::ReadWrite);
QByteArray arr("");
arr.append(data);
file.write(arr);
}