Member class in c++

[dzeko1236]

Hello , I am really new in C++ development .
I am working on Qt Application .
I need to call a member class in another class without creating an instance .
Can I do this ?
thank you

[dutch]

There is no such thing as "calling a class". If you mean calling a member function within a class that is defined within another class, okay, but if you want to do it "without creating an instance" then the member function must be static.

[helios]

The only class members that can be used without an instance are those that are static.

What are you trying to do?

[dzeko1236]

class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    Backend *back;

what i want to do is to get back instance in another class without create a new instance of Mainwindow.
Can I do this please

[doug4]

If the other class has a function that returns a MainWindow reference (MainWindow&), sure.

Maybe if you explained what the other object is, how it contains or references a MainWindow object, and what you want to do with this object, we would be better able to help you.

[dzeko1236]

@doug4
Currently I haven't class which return a reference .

what i have actually :
In Mainwindow :
1/ I have a quickwidget which integrate a qml file .
2/ I create a backend instance to get data from it and fill the QMl File
=> So in MainWindow I have a Backend instance
In Backend
1/I have the definition of my data (getter, setter, change slots).

In UploadCSV
1/I have a button when it's clicked a slot in Backend will change some data .
2/After change data I would like to display it on QML .
=> And in UploadCSV I have another Backend instance

=> the problem is when i create 2 instance I can't get data changed .(and it's logic)
this UploadCSV code:

Backend *back = new Backend(); // this line cause problem 
    connect(ui->parambtn_2, SIGNAL(clicked()),back , SLOT(status()),Qt::QueuedConnection); I must replace back by  th instance created in Mainwindow

I hope is that clear for you
thank you

[doug4]

Rather than explain your code, it would be easier for us if you simply post your code.

[dzeko1236]

thank you all I solve the issue :D :)