[C++Quiz]#27、#41、#44

Question #41

#include <iostream>
int main() {
  std::cout << 1["ABC"];
}

Question #27

#include <iostream>

struct A {
  virtual std::ostream &put(std::ostream &o) const {
    return o << 'A';
  }
};

struct B : A {
  virtual std::ostream &put(std::ostream &o) const {
    return o << 'B';
  }
};

std::ostream &operator<<(std::ostream &o, const A &a) {
  return a.put(o);
}

int main() {
  B b;
  std::cout << b;
}

Question #44

#include <iostream>
struct X {
  virtual void f() const { std::cout << "X"; }
};

struct Y : public X {
  void f() const { std::cout << "Y"; }
};

void print(const X &x) { x.f(); }

int main() {
  X arr[1];
  Y y1;
  arr[0] = y1;
  print(y1);
  print(arr[0]);
}