Untitled

#include <QApplication>
#include <QWidget>
#include <QGridLayout>
#include <QPushButton>

int main(int argc, char *argv[]) {
  QApplication app(argc, argv);
  
  QWidget window;
  
  QGridLayout layout(&window);
  
  QPushButton login("Login");
  
  layout.addWidget(&login, 0, 0);

  window.setLayout(&layout);
  window.show();

  return app.exec();
}

VS

int main(int argc, char *argv[]) {
  QApplication app(argc, argv);
  
  QWidget* window = new QWidget;
  
  QGridLayout* layout = new QGridLayout(window);
  
  QPushButton* login = new QPusButton("Login");
  
  layout->addWidget(login, 0, 0);

  window->setLayout(&layout);
  window->show();

  return app.exec();
}