Problem with variable in main.cpp and mainwindow.cpp

[adis1001]

I made in private, like you, but still isn´t work. While I use a method m.zapisz(51), value 51 is in bit2, or m.bit2? Because if in m.bit2, mainwindow.cpp can´t see this value :/

[stampede]

As a general note, don't define static variables in header files, as each .cpp file which includes the header will get its own copy of the variable.
Typically you only declare the variable in header:

// header.h
extern int my_var;

// header.h
extern int my_var;

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and define it in exactly one .cpp file:

// impl.cpp
#include "header.h"
 
int my_var = 0;

// impl.cpp
#include "header.h"

int my_var = 0;

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In your case I suggest not using the global variable at all anyway.

[adis1001]

Hi, Iḿ not sure I understand you.
I should write extern int bit in private section in mainwindow.h?
And then, where I should write this:

// impl.cpp
#include "header.h"

int my_var = 0;


impl.cpp is my main.cpp or mainwindow.cpp? and int my_var is my bit?

[stampede]

I should write extern int bit in private section in mainwindow.h?

No no, just do that as @jefftee suggested - remove the static variable completely. Use only member variable in the MainWindow class.
I mentioned the "extern" keyword as a sidenote, so that you know it for future.

[adis1001]

Ok, i did it how @jefftee show, but still doesn´t work how I want :/ In main.cpp i have w.zapisz(51), so bit should have value 51, but in mainwindow.cpp bit don´t have a value :/

[anda_skoa]

Are you sure you are reading the variable after your wrote to it?

Cheers,
_

[jefftee]

Repost your current code for all of main.cpp, MainWindow.cpp, and MainWindow.h.