C# 5.0 Programmer's Reference

270 ❘ CHAPTER 12 Classes and Structures
contains methods for manipulating the recipe, so you don’t need to write a separate module containing
methods to convert measurements, scale the recipe, and print. The class keeps all these
things together, so they’re easy to find.
This chapter explains how to define and instantiate classes and structures. It explains the key
differences between classes and structures and provides some recommendations about which to
use under different circumstances.
Classes and structures provide almost exactly the same features. For example, both can have properties,
methods, and events. The following sections start by describing classes. As you read about classes, be
aware that most of those features also apply to structures. Sections later in the chapter explain where
the two differ.
Classes
A class packages data and related behavior. The Recipe class described earlier is an example.
It contains information about a recipe and methods for manipulating its data.
Here’s the syntax for declaring a class.
«attributes» «accessibility» «abstract|sealed|static» «partial»
class name «inheritance»
{
statements
}
The only thing all class declarations require is the class clause (including the class’s name). Everything
else is optional. The following code describes a valid (albeit not very interesting) class.
class Person
{
}
The following sections describe the pieces of the general declaration in detail.
attributes
The optional attributes section is a list of attributes that apply to the class. An attribute further refines
the definition of a class to give more information to the compiler and the runtime system.
Attributes are rather specialized and address issues that arise when you perform specific programming
tasks. For example, if you need to copy instances of the class from one application to another,
you can mark the class with the Serializable attribute. This isn’t something you need to do for
every class. Actually, some attributes are so specialized that you may never use them.
Because attributes are so specialized, they are not described in detail here. (Although Chapter 25,
“Serialization,” says more about serialization.) For more information, consult the Internet and the
online help.
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