How can I access the content of a widget outside the constructor? - qt

Question

I want to display the content I wrote in the QLineEdit widget after clicking on the QPushButton with the function ShowMessage(). How can I access that content outside of the constructor?
Tried putting the QLineEdit object I created in to a private variable.
My CPP file
#include "manualwidget.h"
#include <QLabel>
#include <QLineEdit>
#include <QPushButton>
#include <QHBoxLayout>
#include <QMessageBox>
ManualWidget::ManualWidget(QWidget *parent) : QWidget(parent)
{
QLabel *label = new QLabel(this);
QLineEdit *lineEdit = new QLineEdit(this);
QPushButton *pushButton = new QPushButton(this);
QHBoxLayout *layout = new QHBoxLayout();
label->setText("Enter text:");
pushButton->setText("Ok");
layout->addWidget(label);
layout->addWidget(lineEdit);
layout->addWidget(pushButton);
setLayout(layout);
connect(pushButton,SIGNAL(clicked()),this ,SLOT(showMessage()));
connect(lineEdit, SIGNAL(returnPressed()),this, SLOT(showMessage()));
}
void ManualWidget::showMessage(){
QMessageBox::information(this, "Message", "The text entered in the "
"manual widget window is:\n" + m_lineEdit->text());
}
My header file
#ifndef MANUALWIDGET_H
#define MANUALWIDGET_H
#include <QWidget>
#include <QLineEdit>
class ManualWidget : public QWidget
{
Q_OBJECT
public:
explicit ManualWidget(QWidget *parent = nullptr);
signals:
public slots:
private slots:
void showMessage();
private:
QLineEdit m_lineEdit;
};
#endif // MANUALWIDGET_H

Answer 1

#eyllanesc suggestion might work, but it should not be a prefered approach. Qt has its' own memory model, and usage of it should be prefered. Thus, "QLineEdit m_lineEdit" should be changed to e.g. "QLineEdit* m_lineEdit", and in constructor you should initialize it in the following way:
// Instance of the QLineEdit will be owned by the ManualWidget which is part of Qt memory management now.
m_lineEdit = new QLineEdit(this);
Then, the following line:
layout->addWidget(lineEdit);
Can be changed to:
layout->addWidget(m_lineEdit);
Why is it bad to use "QLineEdit m_lineEdit"? Because Qt might want to destroy this object for some reason (you still can call m_lineEdit.deleteLater()) and you might end up in the "double destruction" situation which would result in app being crashed. You can say that in this way conflicting memory models would interact.