C# 4 and .NET 4

Classes ❘ 67
class PhoneCustomer
{
public const string DayOfSendingBill = "Monday";
public int CustomerID;
public string FirstName;
public string LastName;
}
Events are class members that allow an object to notify a caller whenever something noteworthy happens,
such as a field or property of the class changing, or some form of user interaction occurring. The client can
have code, known as an event handler, which reacts to the event. Chapter 8, “Delegates, Lambdas, and
Events,” looks at events in detail.
function members
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Methods
Function members are those members that provide some functionality for manipulating the data in
the class. They include methods, properties, constructors, finalizers, operators, and indexers.
Methods are functions that are associated with a particular class. Just as with data members, function
members are instance members by default. They can be made static by using the static modifier.
Properties are sets of functions that can be accessed from the client in a similar way to the public
fields of the class. C# provides a specific syntax for implementing read and write properties on your
classes, so you don’t have use method names that have the words Get or Set embedded in them.
Because there’s a dedicated syntax for properties that is distinct from that for normal functions, the
illusion of objects as actual things is strengthened for client code.
Constructors are special functions that are called automatically when an object is instantiated.
They must have the same name as the class to which they belong and cannot have a return type.
Constructors are useful for initialization.
Finalizers are similar to constructors but are called when the CLR detects that an object is no longer
needed. They have the same name as the class, preceded by a tilde (~). It is impossible to predict precisely
when a finalizer will be called. Finalizers are discussed in Chapter 13, “Memory Management
and Pointers.”
Operators, at their simplest, are actions such as + or –. When you add two integers, you are, strictly
speaking, using the + operator for integers. However, C# also allows you to specify how existing
operators will work with your own classes (operator overloading). Chapter 7, “Operators and Casts,”
looks at operators in detail.
Indexers allow your objects to be indexed in the same way as an array or collection.
Note that official C# terminology makes a distinction between functions and methods. In C# terminology,
the term “function member” includes not only methods, but also other nondata members of a class
or struct. This includes indexers, operators, constructors, destructors, and also — perhaps somewhat
surprisingly — properties. These are contrasted with data members: fields, constants, and events.
Declaring Methods
In C#, the definition of a method consists of any method modifiers (such as the method’s accessibility), the
type of the return value, followed by the name of the method, followed by a list of input arguments enclosed
in parentheses, followed by the body of the method enclosed in curly braces:
[modifiers] return_type MethodName([parameters])
{
// Method body
}
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