Data Structures and Algorithms with Object-Oriented Design Patterns in C#

Exercises

1. Specify the set of values and the set of operations provided by each of the following C# types:
   1. char,
   2. int,
   3. double, and
   4. string.
2. What are the features of C# that facilitate the creation of user-defined data types.
3. Explain how each of the following C# features supports polymorphism:
   1. interfaces,
   2. abstract classes,
   3. inheritance, and
   4. operator overloading.
4. Suppose we define two concrete classes, A and B, both of which are derived from the ComparableObject class declared in Program . Furthermore, let a and b be instances of classes A and B (respectively) declared as follows:

   public class A : ComparableObject { ... };
   public class B : ComparableObject { ... };
   ComparableObject a = new A();
   ComparableObject b = new B();

   Give the sequence of methods called in order to evaluate a comparison such as ``a < b''. Is the result of the comparison true or false? Explain.
5. Consider the ComparableInt32 wrapper class defined in Program . Explain the operation of the following program fragment:

   ComparableObject i = 5;
   ComparableObject j = 7;
   bool result = i < j;

6. Let c be an instance of some concrete class derived from the AbstractContainer class given in Program . Explain how the statement

   Console.WriteLine(c);

   prints the contents of the container on the console.
7. Suppose we have a container c (i.e., an instance of some concrete class derived from the AbstractContainer class defined in Program ) which among other things happens to contain itself. What happens when we invoke the ToString method on c?
8. Enumerators and visitors provide two ways to do the same thing--to visit one-by-one all the objects in a container. Give an implementation for the Accept method of the AbstractContainer class that uses an enumerator.
9. Is it possible to implement an enumerator using a visitor? Explain.
10. Suppose we have a container which we know contains only instances of the ComparableInt32 class defined in Program . Design a Visitor which computes the sum of all the integers in the container.
11. Consider the following pair of Associations:

    ComparableObject a = new Association(3, 4);
    ComparableObject b = new Association(3);

    Give the sequence of methods called in order to evaluate a comparison such as ``a == b''. Is the result of the comparison true or false? Explain.

Copyright © 2001 by Bruno R. Preiss, P.Eng. All rights reserved.