How c++ 'this' keyword works with inheritance. Does it take the parent object or the child object?

this_inheritance.cc

// explanation:
// Defines 3 classes: Parent, Child, and Thing.
// Thing takes in a parent into its constructor.
// Parent initializes a Thing in its constructor using 'this.'
// Child does nothing but initialize Parent().
//
// main initializes a Child class, and calls a function from Thing.
// Thing, which was initialized using 'this' in the parent constructor,
// uses that 'this' to refer to the Child, not the Parent.


#include <iostream>

class Parent;

class Thing{
public:
    Thing(Parent* p) : parent(p) {};
    void Print();
    
    Parent* parent;
};

class Parent{
public:
    Parent() : myInt(0) { 
        thing = new Thing(this);
    }
    
    virtual void SetMyInt() { myInt = &parentInt; }
    
    int parentInt = 1;
    int* myInt;
    
    Thing* thing;
};

class Child : public Parent {
public:
    Child() : Parent() { 
        myInt = &childInt; 
    }
    
    void SetMyInt() override { myInt = &childInt; }
    
    int childInt = 2;
};

void Thing::Print() {
    parent->SetMyInt();
    std::cout << *parent->myInt;
}


int main() {
    Child child;
    child.thing->Print();
}

// OUTPUT:
// 2
//
// This proves that even though 'Thing' was initialized in the constructor
// of 'Parent' using the 'this' keyword, 'this' refers to the child
// when the child is initialized, not the parent. This is why calling
// thing->Print() from the child class calls the child's 'SetMyInt()' function,
// not the parent's.