Which of the following statements about friends is correct?

A friend function of a class is a member of the class
B. A friend class of a class is an object member of the class
C. A friend function of a class can access to the private member of the class
D. A friend function of a class is defined outside of the class where it needs to have the class scope

When a copy constructor may be called?

A. When an object of the class is returned by value
B. When an object of the class is passed (to a function) by value as an argument
C. When an object is constructed based on another object of the same class
D. All of the above

An initializer list in a constructor must be used when

A. there is a reference variable in class
B. there is a constant variable in class
C. there is an object of another class. And the other class does not have default constructor
D. All of the above

#include using namespace std;class Test {static int x;public:Test() { x++; }static int getX() { return x; }~Test() {cout << x << " destroying an object\n";x--;}};int Test::x = 0;int main(){Test t[5];cout << Test::getX() << endl;return 0;}what is the output?

#include using namespace std;class A{public:A(){ cout <<"The A object is created\n"; }~A(){ cout << "The A object is destroyed\n"; }};class B{public:B(){ cout << "The B object is created\n"; }~B(){ cout << "The B object is destroyed\n"; }private:A a;};int main(){B b;return 0;}what is the output?

Given the declaration of the A class.class A{public:void print();private:char* p; //allocate a space in free store};1. How do you define a constructor to initialize data member p?2. If there is a statement A a = A() in the test program, whether do you need to define a copy constructor of the A class? How to define a copy constructor?

Given a test program.int main(){A a[10];a[0].setA(40);return 0;}Write the definition of the class according to the test program.