Homework 04 ECE 449/590

Homework 04
ECE 449/590
1. (30 points) Consider the following piece of code. For each definition of the class
A, determine if there will be any compiling error. If so, find the first line with the
error and explain why.
void some_function()
{
A a; // line 1
A b = a; // line 2
b = a; // line 3
}
A. class A
{
const int member;
};
B. class A
{
int member;
~A();
};
C. class B
{
B &operator=(const B &);
};
class A
{
B member;
};
2. (25 points) Read the following program and decide what among the three members
– default constructor, copy constructor, and operator=, should be synthesized or
implemented in type T for the lines 1 to 5 to be compiled correctly. For example,
the line 0 requires none of the three.
1
ECE 449/590 – Object-Oriented Programming and Machine Learning, Fall 2022 2
T create(size_t n);
bool condition_one(T t);
bool condition_two(const T &t);
void modify(T &t);
T generate(size_t n) {
T a(1); // line 0
T b = create(n); // line 1
while (!condition_one(b)) { // line 2
modify(b); // line 3
if (condition_two(b)) // line 4
break;
}
return b; // line 5
}
3. (20 points)
Consider the following class definitions.
class base {
public:
base(bool th) {
std::cout << "ctor of base" << std::endl;
if (th) {
throw std::runtime_error("throw from ctor of base");
}
}
~base() {
std::cout << "dtor of base" << std::endl;
}
};
class member {
public:
member(bool th) {
std::cout << "ctor of member" << std::endl;
if (th) {
throw std::runtime_error("throw from ctor of member");
}
}
~member() {
ECE 449/590 – Object-Oriented Programming and Machine Learning, Fall 2022 3
std::cout << "dtor of member" << std::endl;
}
};
class derived : public base {
member m_;
public:
derived(bool base_th, bool member_th)
: base(base_th), m_(member_th) {
std::cout << "ctor of derived" << std::endl;
}
~derived() {
std::cout << "dtor of derived" << std::endl;
}
};
Determine the outputs of the following functions and explain why.
1) void test_1() {
try {
derived d(false, false);
}
catch (std::exception &e) {
std::cout << e.what() << std::endl;
}
}
2) void test_2() {
try {
derived d(false, true);
}
catch (std::exception &e) {
std::cout << e.what() << std::endl;
}
}
3) void test_3() {
try {
derived d(true, false);
}
catch (std::exception &e) {
std::cout << e.what() << std::endl;
}
}
ECE 449/590 – Object-Oriented Programming and Machine Learning, Fall 2022 4
4) void test_4() {
try {
derived d(true, true);
}
catch (std::exception &e) {
std::cout << e.what() << std::endl;
}
}
4. (25 points) Compile and execute smart_pointer.cpp. Explain the output.