This print for content only-size & color not accurate 7" X 9-1/4" / casebound / malloy

■

Source Code

The FunWithStructures project is located under the Chapter 4 subdirectory.

C H A P T E R   4  

■

C O R E   C #   P R O G R A M M I N G   C O N S T R U C T S, PA RT   I I

128

8849CH04.qxd  10/1/07  10:31 AM  Page 128

---

Understanding Value Types and Reference Types

■

Note

The following discussion of value types and reference types assumes that you have a background in

object-oriented programming. We will examine a number of topics that assume you have a background in object-

oriented programming. If this is not the case, you may wish to reread this section once you have completed

Chapters 5 and 6.

Unlike arrays, strings, or enumerations, C# structures do not have an identically named representa-

tion in the .NET library (that is, there is no System.Structure class), but are implicitly derived from

System.ValueType. Simply put, the role of System.ValueType is to ensure that the derived type (e.g.,

any structure) is allocated on the 

stack rather than the garbage collected heap.

Functionally, the only purpose of System.ValueType is to “override” the virtual methods defined

by System.Object to use value-based, versus reference-based, semantics. As you may know, overrid-

ing is the process of changing the implementation of a virtual (or possibly abstract) method defined

within a base class. The base class of ValueType is System.Object. In fact, the instance methods

defined by System.ValueType are identical to those of System.Object: