CSE2050 Fall 2004 Exam #2, open book, open notes.  Name ___________________

1. Circle True or False (3 pts each).

ANSWERS
T    A struct is a class whose members are public by default.
T    It is good design to make data members private.
  F  new int(10) returns a pointer to an array of 10 ints.  (new int[10] does)
T    new throws bad_alloc if it fails.
  F  Memory allocated with new is deleted when the pointer to it goes
     out of scope.
T    An operator can be overloaded as either a member or nonmember function.
  F  A const member function cannot be called on a non-const object.
T    A const member function should not return a reference to a data member.
T    A constructor taking 1 parameter defines an implicit conversion.
T    If you don't write a constructor initialization list, the compiler
     will add one that initializes all data members with no arguments.

2. Write the constructor code for X using an initialization list (10 pts).

  template <class T> class X {
    int z;
  public:
    X(int a=0);  // set z=a
  };

  // ANSWER
  template <class T>
  X<T>::X(int a): z(a) {}


3. Write class Money and overload + and << as in the example below (30 pts).

  Money a(3, 98), b = 20;  // $3.98, $20.00
  cout << a+b << endl;     // print $23.98

  // ANSWER
  class Money {
    int cents;  // other representations are possible
  public:
    int getCents() const {return cents;}
    Money(int d, int c=0): cents(d*100+c) {}
  };

  Money operator+(const Money& a, const Money& b) {  // could also be a member
    return Money(0, a.getCents()+b.getCents());
  }

  ostream& operator << (ostream& out, const Money& m) {  // must be nonmember
    return out << '$' << m.getCents()/100 << "."
               << setw(2) << setfill('0') << m.getCents()%100;
  }


4.  Given class Person below, add the 3 member functions required by
the rule of 3 (30 pts).

  class Person {
    char *name;  // array of namelen chars
    int namelen;
  public:
    Person(const string& n): name(new char[n.size()]), namelen(n.size()) {
      copy(n.begin(), n.end(), name);
    }

    // ANSWER (see ch. 11.3.6)

    // destructor
    ~Person {delete[] name;}

    // copy constructor
    Person(const Person& p): name(new char[p.namelen]), namelen(p.namelen) {
      copy(p.name, p.name+p.namelen, name);
    }

    // assignment
    Person& operator = (const Person& p) {
      if (&p != this) {  // not assignment to self
        delete[] name;
        name = new char[p.namelen];
        namelen = p.namelen;
        copy(p.name, p.name+p.namelen, name);
      }
      return *this;
    }
  };