Accessing Child class Object from Another Child Class without creating new object in cpp

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I have a scenario where I need to access an object of a child class from another child class I have something like this: In parent.h

#include "child1.h"
#include "child2.h"

class Parent
{
public:

    Child1 Child1_obj;
    Child2 Child2_obj;

    void setVar2_Value(int v2)
    {
        Child2_obj.Var2 = v2;
    }
};

In child1.h

#include "child2.h"
class Child1
{
private:
    int Var1;
public:

    // these below functions are in .cpp file but I am placing here for simplicity to post
    int DoArithmetic()
    {
       int temp1 = Increment_and_Multiply();
       return temp1;
    }
    int Increment_and_Multiply()
    {
        Child2* pChild2;               // How to initialize so I can access the value of the same object created inside Class A, insted of pointing to new Child2 object
        
        // first increment Var2 and then multiply. I want this increment to be reflected  in object created in class A
        pChild2->Var2++;
        return pChild2->Var2 * Var1;
    }
};

In child2.h

#include "Child1.h"
class Child2
{
public:
    int Var2; 
};

In main.cpp

#include "parent.h"
int main()
{
    Parent P1;
    P1.setVar2_Value(5);            // set Var2 value to 5
    int res = P1.Child1_obj.DoArithmetic();
                                    // Var2 value in now 6
    // Do something else                                

}

As mentioned in the comments, I want Child2 class object access from Child1 so I can directly modify its values from Child1 which also get reflected in the object created in the parent class. Any guidance on this will be highly appreciated. Thank you.

class oop c++
1 Answers

Pass a reference to the child when you need access to it. Rather than calling Child1::DoArithmetic let the caller call Parent::Arithmetic:

class Child2
{
public:
    int Var2; 
};

class Child1
{
private:
    int Var1;
public:


    // these below functions are in .cpp file but I am placing here for simplicity to post
    int DoArithmetic(Child2& child2)
    {
       int temp1 = Increment_and_Multiply(child2);
       return temp1;
    }
    int Increment_and_Multiply(Child2& child2)
    {
        // first increment Var2 and then multiply. I want this increment to be reflected  in object created in class A
        child2.Var2++;
        return child2.Var2 * Var1;
    }
};


class Parent
{
public:
    Child1 Child1_obj;
    Child2 Child2_obj;
    int DoArithmetic() {
        return Child1_obj.DoArithmetic(Child2_obj);
    }
    void setVar2_Value(int v2)
    {
        Child2_obj.Var2 = v2;
    }
}; 

int main()
{
    Parent P1;
    P1.setVar2_Value(5);            // set Var2 value to 5
    int res = P1.DoArithmetic();
                                    // Var2 value in now 6
    // Do something else                                

}

PS: Do not define default constructors that do nothing. If you want to declare them then do Child1() = default;. There is also no need to declare the constructor when the compiler can geenrate it for you.

463035818_is_not_a_number0
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