Name______________________________________________________________

1. Let us return to the Fraction class. Relevant parts of the Fraction class definition are listed below:

class Fraction {

public:

//you may assume that copy constructor and operator= are fully implemented

…

private:

int numerator, denominator; //denominator cannot be zero

};

a) (25%) Implement operator^. operator^ would be used by a client as follows:

Fraction f(2,3); //f stores 2/3

Fraction g = f^3; //g stores 8/27

You may assume that exponents are nonnegative integers.

b) (25 %) Implement another version of operator^. This version of operator^ would be used by a client as follows:

Fraction f(2,3); //f stores 2/3

float g = 3.0^f; //g stores 2.08 (which is 3^(0.66667))

Please note: in parts (a) and (b) of the above question, you may assume that the pow function is available (i.e. pow(x,y), where x and y are floats, returns x^y).

a)

Fraction

Fraction::operator^ (int Exponent) {

Fraction result;

result.numerator = pow (numerator, Exponent);

result.denominator = pow (denominator, Exponent);

return result;

}

b)

float operator^ (float RHS, const Fraction& LHS) {

float exp = (double)LHS.numerator/(double)LHS.denominator;

return pow (RHS, exp);

}

2. (22%) What is a pure virtual method? How are pure virtual methods specified syntactically?

A pure virtual method is one that cannot be implemented because there isn’t enough information stored in the class to do so. Syntactically, pure virtuals are specified as follows:

virtual <return-type> <function-name> (parameters list) = 0;

3. (23%) How do programmers use abstract base classes?

According to our textbook an abstract base class “is used only as the basis for derived classes and thus defines a minimum interface for its descendants.”[p. 396]

4. (5%) Why would a function be made a friend of a particular class?

Friendship grants the function so-called direct access to the private members of the class.