Homework 02 ECE 449/590

Homework 02
ECE 449/590
1. (10 points) Consider the following function access_element_by_index that returns the iterator to the element at the index i in the list l.
typedef std::list<int> int_list;
int_list::iterator access_element_by_index(size_t i, int_list &l)
{
assert( ? );
...
}
Assume the first element of the list is at the index 0, the second at the index 1, and
so on. If the function is required to return an iterator that can be dereferenced,
determine the precondition of the function and write an assertion to validate it.
(You don’t need to implement the function.)
2. (20 points)
Consider a container of type std::map<std::string, int>. A C++ function
find_or_throw will search a value from one such container given a key. It will return the value if the key exists and throw std::runtime_error otherwise. Design
the function interface (parameters and return type) and implement the function
body.
3. (20 points) For the course project, two classes program and evaluation are used
at the top level to interact with the Python code. If we would like to support
multiple C++ implementations for evaluation, e.g. a simple implementation, a
second implementation using multi-threading, and a third implementation using
CUDA, how would you modify the current class design so that the changes would
be minimal? Describe your ideas without providing implementation details.
4. (30 points) Assume there is no compiling or linking error. Review the following
pieces of code and briefly explain potential issues.
1
ECE 449/590 – Object-Oriented Programming and Machine Learning, Fall 2022 2
A. std::string &get_hello() {
std::string s = "hello";
return s;
}
B. class time {
int hour, min, sec;
public:
bool set(int h, int m, int s);
int get_hour() const;
int get_min() const;
int get_sec() const;
};
C. class collection {
};
class my_array : public collection {
std::vector<int> vec_;
};
void test() {
collection *p = new my_array;
delete p;
}
5. (20 points) Consider the classes base and derived as follows.
class base {
protected:
virtual void step_one() {std::cout << "base::step_one" << std::endl;}
virtual void step_two() {std::cout << "base::step_two" << std::endl;}
public:
void run() {
std::cout << "enter base::run" << std::endl;
step_one();
step_two();
std::cout << "exit base::run" << std::endl;
}
};
class derived : public base {
protected:
void step_one() {std::cout << "derived::step_one" << std::endl;}
void step_two() {std::cout << "derived::step_two" << std::endl;}
public:
void run() {
ECE 449/590 – Object-Oriented Programming and Machine Learning, Fall 2022 3
std::cout << "enter derived::run" << std::endl;
step_one();
step_two();
std::cout << "exit derived::run" << std::endl;
}
};
A. What’s the output of the following function test1?
void test1() {
derived d;
derived *p = &d;
p->run();
}
B. What’s the output of the following function test2?
void test2() {
derived d;
base *p = &d;
p->run();
}