class

Class

The most common definition states that a class is a template for an object. Suppose that someone builds a paper pattern for a shirt. All the shirts done with the same paper pattern will be identical (same design, size, etc.). In this sample, the paper pattern is the class and the shirt is the object. To build the same exact shirt over and over, you need the paper pattern as a template. Another great example are house plans and blueprints. The plans and blueprints define the number of rooms, the size of the kitchen, the number of floors, and more. In this real world sample, the house plans and blueprints are the class and the house is the object. In OOP you program a class as a template for a specific object or groups ob objects that will always have the same features.

Class members

A class has different members, and developers in Microsoft suggest to program them in the following order:

·         Namespace: The namespace is a keyword that defines a distinctive name or last name for the class. A namespace categorizes and organizes the library (assembly) where the class belongs and avoids collisions with classes that share the same name.

·         Class declaration: Line of code where the class name and type are defined.

·         Fields: Set of variables declared in a class block.

·         Constants: Set of constants declared in a class block.

·         Constructors: A method or group of methods that contains code to initialize the class.

·         Properties: The set of descriptive data of an object.

·         Events: Program responses that get fired after a user or application action.

·         Methods: Set of functions of the class.

·         Destructor: A method that is called when the class is destroyed. In managed code, the Garbage Collector is in charge of destroying objects; however, in some cases developers need to take extra actions when objects are being released, such as freeing handles or deallocating unmanaged objects. In .NET, there is no concept of deterministic destructors. The Garbage Collector will call the Finalize() method at a non-deterministic time while reclaiming memory for the application.

Access keywords

Access keywords define the access to class members from the same class and from other classes. The most common access keywords are:

·         Public: Allows access to the class member from any other class.

·         Private: Allows access to the class member only in the same class.

·         Protected: Allows access to the class member only within the same class and from inherited classes.

·         Internal: Allows access to the class member only in the same assembly.

·         Protected internal: Allows access to the class member only within the same class, from inherited classes, and other classes in the same assembly.

·         Static: Indicates that the member can be called without first instantiating the class.

The following sample code illustrates a sample class in C#: