Passing a variable from MainWindow to new window - c++

Question

In my MainWindow i have a combobox and a select button. When the select button is clicked a new window is opened.
I want to be able to create a QString variable on the MainWindow that contains the text from the combobox, and pass that QString to the new window. The new window is going to perform different tasks, based on the contents of the QString (based on the selection of the combobox).
The following is my code so far...
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "testwindow.h"
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
ui->cmboTestSelect->addItem("{Please Select a Test}");
ui->cmboTestSelect->addItem("Test 1");
ui->cmboTestSelect->addItem("Test 2");
ui->cmboTestSelect->addItem("Test 3");
ui->cmboTestSelect->addItem("Test 4");
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_btnTestSelect_clicked()
{
QString str_TestSelect = ui->cmboTestSelect->currentText(); //stores "Test Name" in string
hide();
Testwindow = new testwindow(this);
Testwindow->show();
}

Answer 1

The simplest way to do this is, as suggested in the comments, to pass the variable as parameter in the constructor of the class Testwindow. Then you can save the value of the string in a private variable in your Testwindow class and do whatever you want with it.
testwindow.h
class Testwindow : public QMainWindow
{
Q_OBJECT
public:
explicit Testwindow(QString text, QWidget *parent = nullptr);
signals:
private:
QString comboBoxText;
};
testwindow.cpp
Testwindow::Testwindow(QString text, QWidget *parent) : QMainWindow(parent)
{
comboBoxText = text; //now you can use comboBoxText in the rest of Testwindow class
}
mainwindow.cpp
void MainWindow::on_btnTestSelect_clicked()
{
QString str_TestSelect = ui->cmboTestSelect->currentText(); //stores "Test Name" in string
hide();
Testwindow *w = new Testwindow(str_TestSelect, this);
w->show();
}