create QT project without using form or qml

[PopQt]

I have some experience in creating x11 applications using xlib. I am new to QT and I don't want to use any of the xlib calls.
I used an empty qt project and added necessary class files in it. I used separate main.cpp and class for mainwindow. Now i would like to create only Qlabel in a separate class and assign mainwindow as it's parent.
Here is my code:
/main.cpp/

#include <QtGui/QApplication>
#include <mainwindow.h>
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    mainWindow mainWin;
    mainWin.showFullScreen();
    a.applicationName();

    return a.exec();
}

/mainwindow.h/

#include <QMainWindow>

class mainWindow : public QMainWindow
{
    Q_OBJECT
public:
    explicit mainWindow(QWidget *parent = 0);
    
signals:
    
public slots:
    
};

/mainwindow.cpp/

#include "mainwindow.h"

mainWindow::mainWindow(QWidget *parent) :
    QMainWindow(parent)
{
}

/baseTextWin.h/

#include <QLabel>
#include <QString>
class baseTextWin
{
public:
    QLabel* textWin;

    baseTextWin(,int x, int y, int width, int height); //would like to set mainwindow as parent
    void showTextWin();
    void hideTextWin();
};

/baseTextWin.cpp/

#include "basetextwin.h"

baseTextWin::baseTextWin(int x, int y, int width, int height)
{
    textWin = new QLabel;
    textWin->setGeometry(x, y, width, height);

    hideTextWin();
}
void baseTextWin::showTextWin() {
    textWin->show();
}

void baseTextWin::hideTextWin() {
    textWin->hide();
}

now when I execute this, I get as separate windows. I want everything in one main window.

[JKSH]

Hi @PopQt, you said you "would like to set mainwindow as parent". To do that, pass the parent widget's pointer into the child widget's constructor.

Example:

mainWindow::mainWindow(QWidget *parent) :
    QMainWindow(parent)
{
    // Create a QLabel which shows the word "Hello",
    // and is nested inside this main window
    auto label = new QLabel("Hello", this);
    // ...
}

[PopQt]

Thank you very much @JKSH . It worked.