Member access operators

#include <iostream>
 
int main()
{
    int a[4] = {1,2,3,4};
    int* p = &a[2];
    std::cout << p[1] << p[-1] << 1[p] << (-1)[p] << '\n';
}

#include <iostream>
int f() { return 42; }
int main()
{
    int n = 1;
    int* pn = &n;
 
    int& r = *pn;  // lvalue can be bound to a reference
    int m = *pn;   // indirection + lvalue-to-rvalue conversion
 
    int (*fp)() = &f;
    int (&fr)() = *fp; // function lvalue can be bound to a reference 
}

void f(int) {}
void f(double) {}
struct A { int i; };
struct B { void f(); };
int main()
{
    int n = 1;
    int* pn = &n; // pointer
    int A::* mp = &A::i;  // pointer to member object
    void (B::*mpf)() = &B::f; // pointer to member function
 
//    auto pf2 = &f; // error: ambiguous overloaded function type
    void (*pf)(int) = &f; // overload resolution due to initialization
    auto pf2 = static_cast<void(*)(int)>(&f); // overload resolution due to cast
}

#include <iostream>
template<typename T>
struct P { typedef T* ptr; };
template<typename T>
struct A {
    class B {};
    enum E {RED = 1, BLUE = 2};
    int n;
    static int sn;
    int f() { return 10+n; }
    static int fs() { return 4; }
    A(int n) : n(n) {}
 
    // keyword template needed to refer to a dependent template member
    void g() {
        T obj;
        int* p = obj.template ptr<int>;
        p->~T(); // T is int, this calls int's pseudo destructor
    }
};
template<> int A<P<int>>::sn = 2;
 
int main()
{
    A<P<int>> a(1);
    std::cout << a.n << ' '
              << a.sn << ' ' // << A::sn also works
              << a.f() << ' ' 
              << a.fs() << ' ' // A::fs() also works
              << a.RED << ' '  // nested type not allowed
//            << a.B  // nested type not allowed
              ;
}

#include <iostream>
struct S
{
    mutable int mi;
    int f(int n) { return mi+n; }
    S(int n) : mi(n) {}
};
struct D : public S {
        D(int n) : S(n) {}
};
 
int main()
{
    int S::* pmi = &S::mi;
    int (S::*mpf)(int) = &S::f;
 
    const S s(7);
//    s.*pmi = 10; // cannot modify through mutable
    std::cout << s.*pmi << '\n';
 
    D d(7); // base pointers work with derived object
    D* dp = &d;
    std::cout << (d.*mpf)(7) << ' '
              << (dp->*mpf)(8) << '\n';
}