3.3. Overview of Class Members

Table 3-1 provides a summary of the types that comprise a .NET class. They can be classified broadly as members that hold data constants, fields, and properties and members that provide functionality the constructor, method, and event. We'll look at each individually.

Table 3-1. Class Members

Member Type	Valid In	Description
Constant	Class, Structure	A symbol that represents an unchanging value. The compiler associates it with the class not an instance of the class.
Field	Class, Structure	A variable that holds a data value. It may be read-only or read/write.
Property	Class, Structure	Provides access to a value in a class. It uses an accessor that specifies the code to be executed in order to read or write the value. The code to read or write to a property is implemented implicitly by .NET as two separate methods.
Constructor	Class, Structure	C# has three types of constructors: Instance. Initializes fields when an instance of a class is created. Private. Commonly used to prevent instances of a class from being created. Static. Initializes class before any instance is created.
Method	Class, Structure, Interface	A function associated with the class that defines an action or computation.
Events	Class, Structure, Interface	A way for a class or object to notify other classes or objects that its state has changed.
Types	Class, Structure, Interface	Classes, interfaces, structs, delegates.

Member Access Modifiers

The access modifiers used for a class declaration can also be applied to class members. They determine the classes and assemblies that have access to the class. Table 3-2 summarizes the scope of accessibility.

Table 3-2. Summary of Accessibility Provided by Access Modifiers

	Access Modifiers
Class can be accessed by classes in:	Public	protected	Internal	private
Another assembly	Yes	[*]	No	[*]
Same assembly	Yes	[*]	Yes	[*]
Containing class	Yes	Yes	Yes	Yes
Class derived from containing class	Yes	Yes	Yes	No

^[*] Not applicable