Создание виджета через код

QLabel* pLabel=new QLabel(this);
pLabel->setText("Ho-lo-lo!");

#ifndef WIDGET_H
#define WIDGET_H
 
#include <QtWidgets>
 
class Widget : public QWidget
{
    Q_OBJECT
private:
    QLabel* m_pLabel;
    QPushButton* m_pPushButton;
    QVBoxLayout* m_pVBoxLayout;
 
 
public:
    Widget(QWidget *parent = nullptr);
    ~Widget();
private slots:
    void slotPushButtonClicked();
};
#endif // WIDGET_H

#include "Widget.h"
 
Widget::Widget(QWidget *parent)
    : QWidget(parent), m_pLabel(nullptr), m_pPushButton(nullptr), m_pVBoxLayout(nullptr)
{
   m_pLabel=new QLabel("Hello Parent!");
   m_pPushButton=new QPushButton("Click Me!");
   QObject::connect(m_pPushButton, SIGNAL(clicked(bool)),
                    this, SLOT(slotPushButtonClicked()));
 
   m_pVBoxLayout=new QVBoxLayout;
   m_pVBoxLayout->addWidget(m_pLabel);
   m_pVBoxLayout->addWidget(m_pPushButton);
   setLayout(m_pVBoxLayout);
   setObjectName("Main Widget");
}
 
Widget::~Widget()
{
}
 
void Widget::slotPushButtonClicked()
{
    QString parentsStr=m_pLabel->parent()->objectName() + "\n" +
            m_pPushButton->parent()->objectName() + "\n" +
            m_pVBoxLayout->parent()->objectName();
    QMessageBox::information(this, "Parents info", parentsStr);
}

QWidget * mainWidget = new QWidget;
QVBoxLayout * mainLayout = new QVBoxlayout;
QLabel * label = new QLabel;
mainLayout->addWidget(label) // mainLayout предок label
mainWidget->setLayout(mainLayout) // mainWidget предок mainLayout