Accessing the variable of class a into calss b function in c++

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Lets say I have my main class declared in a header file, and defined in a cpp file.
classA.h

C++

#ifndef MAIN_H_
#define MAIN_H_

#include <iostream>

class ClassA
{
public:

     ClassA()
     {
     }

     ~ClassA()
     {
     }

     int i = 3
    
protected:

     void function(void);
};

#endif 



ClassA::function();

return 0;

Now let's say I have a 2nd class, ClassB.
Secondclass.h

C++

#ifndef HEADER_H_
#define HEADER_H_

#include <iostream>

class Secondclass
{
public:

     int ii = classAObj.i;  //i think this is wrong method
}

I just need to pass variables between classes(ClassA and ClassB). so i can access(display/update) the value of variable i from classB

Thanks for any help, I appreciate it.

What I have tried:

i tried what i mentioned above...

Posted 8-Mar-16 23:24pm

XamBEE

Updated 9-Mar-16 0:02am

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Philippe Mori 9-Mar-16 12:28pm

Learn the langage first! Read books or tutorials.

And usually you don't want to access variable in another class.

1 solution

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Taulie · Answer 1 · 2016-03-09T00:02:00

Solution 1

you need an interface between the classes.
save a pointer of class b in class a and save a pointer of class a in class b if nessessary.
then you have access in both classes to the other class.

Example for classB with access to classA
class classB
{
public:
classB(classA *cA)
{
this->cA = cA;
}

void function()
{
this->cA->i = 5; // example
}

private:
classA *cA;
}

Posted 9-Mar-16 0:02am

Taulie

Updated 9-Mar-16 0:06am

v3

Comments

XamBEE 9-Mar-16 6:44am

would be nice if you add comments what you are doing each line. I didnt get it fully
Thanks for help, I appreciate it.

W∴ Balboos, GHB 9-Mar-16 7:01am

Any reason you cannot use inheritance and having class b inherit a public or protected member class a?