How to use automatically added Qt-elements - c++

Question

My programm can add new QLabels and QLineEdits to a QScrollArea after a button is clicked. The idea is to create a grocery list. My problem is when a second Button is clicked I want to get the text of all the QLineEdits. But I don't know how to use those elements, because every new QLineEdit-variable has the same name and I don't know how to change that.
Below is a small example:
my MainWindow.h:
#ifndef MainWINDOW_H
#define MainWINDOW_H
#include <QMainWindow>
#include <string>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
int i;
private:
Ui::MainWindow *ui;
private slots:
void on_create_clicked();
read_text();
};
#endif // MainWINDOW_H
my MainWindow.cpp:
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
connect(ui->pushButton, SIGNAL(clicked()), this, SLOT(on_create_clicked()));
connect(ui->pushButton_2, SIGNAL(clicked()), this, SLOT(read_text()));
i = 1;
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_create_clicked()
{
if(i < 10)
{
i ++;
QLabel *label_2 = new QLabel();
QString s = QString::number(zaehlerHeight) + ". ";
label_2->setText(s);
ui->scrollArea->widget()->layout()->addWidget(label_2);
QLineEdit *lineEdit = new QLineEdit();
ui->scrollArea_2->widget()->layout()->addWidget(lineEdit);
}
else{
ui->label->setText("already 10");
}
}
void MainWindow::read_text()
{
QString mytext = ui->lineEdit->text();
}

Answer 1

I would simply store the pointer to each QLineEdit in a QVector, and then loop in this vector to get the text of each.
Header:
#ifndef MainWINDOW_H
#define MainWINDOW_H
#include <QMainWindow>
#include <string>
#include <QVector>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
int i;
private:
Ui::MainWindow *ui;
QVector<QLineEdit *> m_VecLineEdits;
private slots:
void on_create_clicked();
private:
void read_text();
void GetAllTextEdit();
};
#endif // MainWINDOW_H
In Cpp file, change the following:
void MainWindow::on_create_clicked()
{
if(i < 10)
{
i ++;
QLabel *label_2 = new QLabel();
QString s = QString::number(zaehlerHeight) + ". ";
label_2->setText(s);
ui->scrollArea->widget()->layout()->addWidget(label_2);
QLineEdit *lineEdit = new QLineEdit();
m_VecLineEdits.push_back(lineEdit); // <-- Line added here to save the pointers in a QVector.
ui->scrollArea_2->widget()->layout()->addWidget(lineEdit);
}
else{
ui->label->setText("already 10");
}
}
void MainWindow::GetAllTextEdit()
{
for(int j = 0; j<m_VecLineEdits.size(); ++j)
{
QString lineEditText = m_VecLineEdits.at(j)->text();
/* Do anything with this value */
}
}
If you delete your QLineEdit, remember to also remove them from the QVector.

Answer 2

If you want to change the name of the variable ( ie the pointer to the QLineEdit ) each time you slot is called, and provided that i will stay small ( < 10 ), you can use switch(i) for example and choose a different variable name for each case, but you will have to store all those variables as members of your class. So it's better to store the pointers in a QList or a QVector and loop over those containers to access the text() method on each QLineEdit.

Answer 3

you can't, because you don't have any pointer or reference to those objects, one solution would be having a array of QLabel in your class definition.
ex:
QVector<QLabel*> _labels;
and adding and instantiating one by one with the press of the button and then you will have the whole list of objects, thus their names