QT5 进度条传文件

void myDialog::on_pushButton_5_clicked()
{
    QProgressDialog dialog(tr("文件复制进度"), tr("取消"), 0 ,50000, this);
    dialog.setWindowTitle(tr("文件复制进度条"));
    dialog.setWindowModified(Qt::WindowModal);
    dialog.show();
    for(int i = 0; i < 50000; i++)
    {
        //设置进度条当前值
        dialog.setValue(i);
        //避免界面冻结
        QCoreApplication::processEvents();
        //如果按了取消，怎提前中断
        if(dialog.wasCanceled()) break;
    }
    //这样在才能显示100%
    dialog.setValue(50000);
    qDebug() << tr("文件传输结束");
}