C++ Quiz #4

This is a test of your knowledge of C++, not of your compiler’s knowledge of C++. Using a compiler during this test will likely give you the wrong answers, or at least incomplete ones.

1. What is the value of i after the first numbered line is evaluated?
2. What do you expect the second numbered line to print out?
3. What is the value of p->c after the third numbered line is evaluated?
4. What does the fourth numbered line print?

struct C;

void f(C* p);

struct C {
	int c;
	C() : c(1) {
		f(this);
	}
};

const C obj;
void f(C* p) {
	int i = obj.c << 2;             //1
	std::cout<< p->c <<std::endl;   //2
	p->c = i;                       //3
	std::cout<< obj.c << std::endl; //4
}

5. What should you expect the compiler to do on the first numbered line? Why?

6. What should you expect the value of j to be after the second numbered line is evaluated? Why?

struct X {
	operator int() {
		return 314159;
	}
};

struct Y {
	operator X() {
		return X();
	}
};

Y y;
int i = y;     //1
int j = X(y);  //2

7. What should you expect the compiler to do on the first and second numbered lines? Why?

struct Z {
	Z() {}
	explicit Z(int) {}
};

Z z1 = 1;                 //1
Z z2 = static_cast<Z>(1); //2

8. What should you expect the behavior of each of the numbered lines, irrespective of the other lines, to be?

struct Base {
	virtual ~Base() {}
};

struct Derived : Base {
	~Derived() {}
};

typedef Base Base2;
Derived d;
Base* p = &d;
void f() {
	d.Base::~Base();    //1
	p->~Base();         //2
	p->~Base2();        //3
	p->Base2::~Base();  //4
	p->Base2::~Base2(); //5
}