Can an object pass itself to a function (not part of a class i.e. global scope), which modifies that object.

[ImC0nfused]

I'm confused as to how to achieve that, most of the examples i have seen have methods present in another class which we instantiate in our object class and use "this" pointer for example anotherclass.foo(this);. Any example would be appreciated.
So currently, the example i am using is this:

class Eater{
public:
   bool isEating=false;
   void goingtoEat(Eater man){ eating(this); }
}
void eating(Eater& man2){
man2.isEating=true;}

But its throwing errors :(

[Ganado]

this is a pointer.
You can deference the pointer to get a reference.

// forward declaration
class Eater;
void eating(Eater& man2);

class Eater{
public:
    bool isEating = false;
    
    void goingtoEat(Eater man){
        eating(*this);
    }
};

void eating(Eater& man2){
    man2.isEating = true;
}

int main()
{
    Eater eater;
    Eater other;
    
    eater.goingtoEat(other);
}

Side note: I realize your example might just be contrived for demonstration, but the 'Eater man' parameter is never used.

History note: Stroustrup introduced the 'this' pointer before references were introduced.

[ImC0nfused]

Oh then what would be the addition/deletion in the above code if'Eater man' is never used. And yes it just a special example and is an unpreferable way of writing a code.

[ImC0nfused]

I have figured it out, for anyone else the final code would be

// forward declaration
class Eater;
void eating(Eater& man2);

class Eater{
public:
    bool isEating = false;
    
    void goingtoEat(){
        eating(*this);
    }
};

void eating(Eater& man2){
    man2.isEating = true;
}

int main()
{
    Eater eater;
    eater.goingtoEat();
}