Programming C#, Third Edition

Using Static Members

The properties and methods of a class can be either instance members or static members. Instance members are associated with instances of a type, while static members are considered to be part of the class. You access a static member through the name of the class in which it is declared. For example, suppose you have a class named Button and have instantiated objects of that class named btnUpdate and btnDelete. Suppose as well that the Button class has a static method SomeMethod( ). To access the static method, you write:

Button.SomeMethod( );

rather than writing:

btnUpdate.SomeMethod( );

In C#, it is not legal to access a static method or member variable through an instance, and trying to do so will generate a compiler error (C++ programmers, take note).

Some languages distinguish between class methods and other (global) methods that are available outside the context of any class. In C# there are no global methods, only class methods, but you can achieve an analogous result by defining static methods within your class.

Note

VB6 programmers take note: Don’t confuse the static keyword in C# with the Static keyword in VB6 and VB.NET. In Visual Basic, the Static keyword declares a variable that is only available to the method it was declared in. In other words, the Static variable is not shared among different objects of its class (i.e., each Static variable instance has its own value). However, this variable exists for the life of the program, which allows its ...