Problem with show Model-View-Deleaget inside MainWindow class

[TomASS]

Hello,

I'm trying code a Model-View-Deleage and I've one question:

When I'm writting this code:

QStandardItemModel model( 5, 2 );
    for( int r=0; r<5; r++ )
    for( int c=0; c<2; c++)
        {
            QStandardItem *item = new QStandardItem( QString("Row:%1, Column:%2").arg(r).arg(c) );
            if( c == 0 )
            for( int i=0; i<3; i++ )
            item->appendRow( new QStandardItem( QString("Item %1").arg(i) ) );
            model.setItem(r, c, item);
        }
 
    QTableView *table = new QTableView;
    table->setModel(&model);
    table->show();

QStandardItemModel model( 5, 2 );
    for( int r=0; r<5; r++ )
    for( int c=0; c<2; c++)
        {
            QStandardItem *item = new QStandardItem( QString("Row:%1, Column:%2").arg(r).arg(c) );
            if( c == 0 )
            for( int i=0; i<3; i++ )
            item->appendRow( new QStandardItem( QString("Item %1").arg(i) ) );
            model.setItem(r, c, item);
        }

    QTableView *table = new QTableView;
    table->setModel(&model);
    table->show();

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into a:

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

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then when application is running there are two windows. First whith:

MainWindow w;
    w.show();

MainWindow w;
    w.show();

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and the second with:

QTableView *table = new QTableView;
    table->setModel(&model);
    table->show();

QTableView *table = new QTableView;
    table->setModel(&model);
    table->show();

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and everything is ok, but, when I write a

QStandardItemModel model( 5, 2 );
    for( int r=0; r<5; r++ )
    for( int c=0; c<2; c++)
        {
            QStandardItem *item = new QStandardItem( QString("Row:%1, Column:%2").arg(r).arg(c) );
            if( c == 0 )
            for( int i=0; i<3; i++ )
            item->appendRow( new QStandardItem( QString("Item %1").arg(i) ) );
            model.setItem(r, c, item);
        }
 
    QTableView *table = new QTableView;
    table->setModel(&model);
    table->show();

QStandardItemModel model( 5, 2 );
    for( int r=0; r<5; r++ )
    for( int c=0; c<2; c++)
        {
            QStandardItem *item = new QStandardItem( QString("Row:%1, Column:%2").arg(r).arg(c) );
            if( c == 0 )
            for( int i=0; i<3; i++ )
            item->appendRow( new QStandardItem( QString("Item %1").arg(i) ) );
            model.setItem(r, c, item);
        }

    QTableView *table = new QTableView;
    table->setModel(&model);
    table->show();

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into:

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent), ui(new Ui::MainWindowClass)
{
    ui->setupUi(this);
//here!
 
}

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent), ui(new Ui::MainWindowClass)
{
    ui->setupUi(this);
//here!

}

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there are a empty window whith table->show() ? why?
when I'm trying put this code into button click:

void MainWindow::on_pushButton_clicked()
{
     QStandardItemModel model( 5, 2 );
    for( int r=0; r<5; r++ )
    for( int c=0; c<2; c++)
        {
            QStandardItem *item = new QStandardItem( QString("Row:%1, Column:%2").arg(r).arg(c) );
            if( c == 0 )
            for( int i=0; i<3; i++ )
            item->appendRow( new QStandardItem( QString("Item %1").arg(i) ) );
            model.setItem(r, c, item);
        }
 
    QTableView *table = new QTableView;
    table->setModel(&model);
    table->show();
}

void MainWindow::on_pushButton_clicked()
{
     QStandardItemModel model( 5, 2 );
    for( int r=0; r<5; r++ )
    for( int c=0; c<2; c++)
        {
            QStandardItem *item = new QStandardItem( QString("Row:%1, Column:%2").arg(r).arg(c) );
            if( c == 0 )
            for( int i=0; i<3; i++ )
            item->appendRow( new QStandardItem( QString("Item %1").arg(i) ) );
            model.setItem(r, c, item);
        }

    QTableView *table = new QTableView;
    table->setModel(&model);
    table->show();
}

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I get a empty window too :/

Thanks!