C++ :: Member Function Pointer Assignment?

I have a class with member functions and a pointer like this:

Code:
class MyClass{
private:
typedef void(MyClass::*memFnPtr_t) ();
public:
memFnPtr_t fnptr;
void fn1();
void fn2();
};

Now in a regular function I create an instance of the class and try to assign the pointer:

Code:
MyClass mc;
mc.fnptr = &mc.fn1;

The compiler does not like it and suggests this instead:

Code:
mc.fnptr = &MyClass::fn1;

This seems to work but what if I have two instances of the class:

Code:
MyClass mc1, mc2;

How does the compiler know to distinguish between

Code:
mc1.fn1

and

Code:
mc2.fn1

when the assignment now looks identical:

Code:
mc1.fnptr = &MyClass::fn1;
mc2.fnptr = &MyClass::fn1;