Chapter 13 - Sets

Summary

A set is a collection of unique elements. The elements of a set are called members. The two most important properties of sets are that the members of a set are unordered and no member can occur in a set more than once. Sets play a very important role in computer science but are not included as a data structure in C#.

This chapter discusses the development of a Set class. Rather than providing just one implementation, however, we provide two. For nonnumeric items, we provide a fairly simple implementation using a hash table as the underlying data store. The problem with this implementation is its efficiency. A more efficient Set class for numeric values utilizes a bit array as its data store. This forms the basis of our second implementation.

FUNDAMENTAL SET DEFINITIONS, OPERATIONS AND PROPERTIES

A set is defined as an unordered collection of related members in which no member occurs more than once. A set is written as a list of members surrounded by curly braces, such as {0,1,2,3,4,5,6,7,8,9}. We can write a set in any order, so the previous set can be written as {9,8,7,6,5,4,3,2,1,0} or any other combination of the members so that all members are written just once.