CSE2050 Spring 2005 Exam #2, open book, open notes.  Name _________________

1. Given the following implementation of class Complex, add the
destructor, copy constructor and assignment operator (40 pts).

  template <class T>
  class Complex {
    T *rp, *ip;  // pointers to real and imaginary parts
  public:
    T real() const {return *rp;}
    T imag() const {return *ip;}
    Complex(T r=0, T i=0): rp(new T(r)), ip(new T(i)) {}

    // ANSWER
    ~Complex() {
      delete rp;  // no []
      delete ip;
    }

    Complex(const Complex& c): rp(new T(c.real())), ip(new T(c.imag())) {}

    Complex& operator = (const Complex& c) {  // or complex<T>&
      *rp = c.real();  // or *rp = *c.rp;
      *ip = c.imag();
      return *this;
    }
  };


2. Write a templated operator << to output Complex<T> in the form "x+yi",
for example (20 pts).

  Complex<int> a(3, 4);
  const Complex<double> d=2.5;
  cout << a << " " << d << endl;  // 3+4i 2.50000+0.00000i

  // ANSWER
  template <class T>
  ostream& operator << (ostream& out, const Complex<T>& c) {
    out << c.real() << "+" << c.imag() << "i";
    return out;
  }


3. How many Complex<int> objects are created in each of the following
statements?  Assume that the arithmetic operators are overloaded with
their usual meaning and that their operands are passed by const reference
and returned by value (4 pts each).
                                                 ANSWERS
  Complex<int> a(1, 2), b=3, c=a, d, e[10], *p;  14 (10 in e, none in p)
  cout << a+5;                                   2 (temp 5+0i and 6+2i)
  a=b;                                           0
  a=b.real();                                    1 (temp 3+0i)
  p=new Complex<int>(5);                         1 (5+0i)

4. Circle True or False (4 pts each).

 ANS.
  F  The "const" in real() means it returns a constant.
  F  The "const" in imag() means it can only be called on a const object.
  F  real() returns by reference.
  T  The Complex<T> constructor parameters are copies of the arguments.
  T  A function should not return a local variable by reference.

  (The "const" in real()/imag() means that they do not modify the object
   and therefore they may be called on a const object.  real() returns
   by value.)