Inheritance CPPE2 M2 Test

Inheritance CPPE2 M2 Test

Inheritance CPPE2 M2 Test

  1. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class A {
public:
    A() : val(0) {}
    int val;
    int inc() { ++val; return val--; }
};

void Do(A *a) {
    a-> val = a->inc() ;
}

int main(void) 
{
   A a;
   Do(&a);
   cout << a.inc();
   return 0;
}
    • 0
    • 1
    • Compilation fails
    • 2

  2. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class A {
friend class B;
private:
    int field;
public:
    int set(int x) { return field = ++x; }
    int get() { return ++field; }
};

class B {
public:
    void kill(A &a) { a.field = 0; }
};

int main(void) 
{
   A a; B b;
   a.set(1);
   b.kill(a);
   cout << a.get();
   return 0;
}
    • Compilation fails
    • 1
    • 2
    • 0

  3. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class X {
private:
    int v;
};

class Y : public X {
   Y() : v(0) {}
}

int main() 
{
  Y y;
  cout << y.v;
  return 0;
}
    • Compilation fails
    • 1
    • 0
    • -1

  4. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class X {
public:
    virtual void shout() { cout << "X"; }
};

class Y : public X {
public:
    void shout() { cout << "Y"; }
};

class Z : public Y {
public:
   void shout() { cout << "Z"; }
};

int main() 
{
   Z *z = new Z();
   static_cast<Y *>(z) -> shout();
   return 0;
}
    • X
    • Y
    • Z
    • Compilation fails

  5. What is the output of the following snippet?

    #include <iostream>
using namespace std;

class X {
public:
    void shout() { cout << "X"; }
};
class Y : public X {
public:
    virtual void shout() { cout << "Y"; }
};

class Z : public Y {
public:
    void shout() { cout << "Z"; }
};

int main() 
{
   Y *y =  new Z();
   dynamic_cast<X *>(y) -> shout();
   return 0;
}
    • Compilation fails
    • X
    • Y
    • Z

  6. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class A {
friend void f();
private:
    int field;
public:
    int set(int x) { return field = ++x; }
    int get() { return ++field; }
};

void f(A &a) {a.field /=2;}

int main() 
{
   A a;
   a.set(2);
   f(a);
   cout << a.get();
   return 0;
}
    • 2
    • 0
    • Compilation fails
    • 1

  7. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class X {
protected:
   int v;
};

class Y : protected X {
   Y() : v(0) {}
}
int main() 
{
   Y *y = new Y();
   cout << y->v;
   delete y;
   return 0;
}
    • -1
    • 1
    • 0
    • Compilation fails

  8. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class A {
public:
    A() : val(0) {}
    int val;
    void inc() { ++val; }
};

void Do(A a) {
    a.inc();
}

int main(void) 
{
   A a;
   Do(a);
   a.inc();
   cout << a.val;
   return 0;
}
    • 0
    • 2
    • Compilation fails
    • 1

  9. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class X {
public:
    virtual void shout() { cout << "X"; }
};

class Y : public X {
public:
   void shout() { cout << "Y"; }
};

class Z : public Y {
public:
   void shout() { cout << "Z"; }
};

int main(void) 
{
   Y *y = new Z();
   dynamic_cast<X *>(y) -> shout();
   return 0;
}
    • Z
    • Compilation fails
    • Y
    • X

  10. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class A {
    int *val;
public:
    A() { val = new int; *val = 0; }
    int get() { return ++(*val); }
};

int main(void) 
{
   A a,b = a;
   cout << a.get() << b.get();
   return 0;
}
    • 22
    • 20
    • 12
    • Compilation fails

  11. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class X {
public:
    void shout() { cout << "X"; }
};

class Y : public X {
};

class Z : public Y {
public:
    void shout() { cout << "Z"; }
};

int main() 
{
   Z *z = new Z();
   static_cast<Y *>(z) -> shout();
   return 0;
}
    • Y
    • X
    • Compilation fails
    • Z

  12. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class A {
public:
    A() : val(0) {}
    int val;
    virtual void run() { cout << val; }
};

class B : public A {
};

class C : public B {
public:
   void run() { cout << val + 2; }
};

void Do(A *a) {
    B *b;
    C *c;
    if(b = dynamic_cast<B *>(a))
       b->run();
    if(c = dynamic_cast<C *>(a))
       c->run();
    a->run();
}

int main() 
{
   A *a = new C();;
   Do(a);
   return 0;
}
    • 210
    • 222
    • Compilation fails
    • 212

  13. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class A {
public:
    int v;
    A(int x) : v(x + 1) {}
    int get() const { return v; }
};

int main() 
{
   A a(2);
   A b(a);
   cout << a.get() << b.get();
   return 0;
}
    • 23
    • 13
    • 33
    • Compilation fails

  14. What is the output of the following snippet?

    #include <iostream>
using namespace std;

class X { };
class Y : public X { };
class Z : public X { };

int main() 
{
   Z *z = new Z();
   X *x = new X();
   x = z;
   cout << (x == z);
   return 0;
}
    • 0
    • -1
    • Compilation fails
    • 1

  15. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class X {
public:
    void shout() { cout << "X"; }
};

class Y : public X {
public:
    void shout() { cout << "Y"; }
};

int main() 
{
   X *x = new Y();
   static_cast<Y *>(x) -> shout();
   return 0;
}
    • Compilation fails
    • X
    • Y
    • It prints nothing

  16. What is the output of the following snippet?

    #include <iostream>
using namespace std;

class X { };
class Y : public X { };
class Z : public X { };
int main() 
{
   Z *z = new Z();
   Y *y = new Y();
   z = y;
   cout << (z == y);
   return 0;
}
    • 0
    • -1
    • 1
    • Compilation fails

  17. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class X {
public:
   int v;
   void put(int x) { v =x; }
   int get(void) { return v; }
};

class Y : public X {
public:
   Y() { put(0); }
   void write(int x) { put(x + 1); }
   int read(void) { return get() - 1; }
};

int main() 
{
   Y *y = new Y();
   y ->write(1);
   cout << y->read();
   delete y;
   return 0;
}
    • 1
    • -1
    • Compilation fails
    • 0

  18. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class A {
public:
    const int v;
    A(int x) : v(x + 1) {}
    int get() { return ++v; }
};

int main() 
{
   A a(2);
   cout << a.get();
   return 0;
}
    • 2
    • 1
    • 3
    • Compilation fails

  19. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class A {
    int *val;
public:
   A() { val = new int; *val = 0; }
   A(A &a) { val = new int; *val = a.get(); }
   int get() { return ++(*val); }
};

int main() 
{
   A a,b = a;
   cout << a.get() << b.get();
   return 0;
}
    • 20
    • Compilation fails
    • 22
    • 21

  20. What is the output of the following snippet?

    #include <iostream>
using namespace std;
class A {
public:
    A() : val(0) {}
    int val;
    void run() { cout << val; }
};

class B : public A {
public:
    virtual void run() { cout << val + 2; }
};

class C: public B {
};

void Do(A *a) {
   B *b;
   C *c;
   if(b = static_cast<B *>(a))
      b->run();
   if(c = dynamic_cast<C *>(b))
      c->run();
   a->run();
}
int main(void) 
{
   A *a =new C();;
   Do(a);
   return 0;
}
    • Compilation fails
    • 220
    • 222
    • 221