Why can the private members of the actual parameters be directly accessed in the copy constructor?

lfq372

Why can you directly access the private members of the actual parameters in the copy constructor?
Such as:
class demo
{
        private:
                int i;
        public:
                demo();
                demo(const demo&);
};

demo::demo(const demo&obj)
{
        i = obj.i; "Private members are used directly here!
}

This can be compiled, why?

gwlwmm

To distinguish that a member function of a class can access any member of the class, not just an object
Your own member function can access any of your own members, through the member function of each object you can access the object
Any member of other objects of the same type.

jotoos

Yes, access permissions are for the class, not for the object.

stealth

A member function of a class can access any member of the class, so it must be able to access the private variable int i in the class in this file.

hzxszmh

I am my friend function

chengwei2537

There's nothing more to say, grasping the foundation is the right way

diamond52

Because the member function has a hidden this pointer to point to the main object
such as
class A
{
public:
    void ok(int i){a = i;}
private:
    int a;
}

int main()
{
    A a;
    a.ok(3);
    return 0;
}
The compiler will parse a.ok() like this (just a model)
ok(int i, A *this)
{
    this -> a = i;
}
That's what I mean
{
}

diamond52

i = obj.i
======
The obj.i on the right can be used directly
Is determined by the process of class domain name resolution,
Inside the member function, when parsing the name, first look at the local domain of the function, and then the entire class domain (they can be accessed without distinguishing between public, private, and protected)
The grammatical rules of C++, the compiler implements it like this, just understand

julines

hzxszmh
   
I am my friend function

learned

clackhyf

This has nothing to do with copy construction, any member function can be, because they are the same class