Learn C# programming - Interfaces & Namespaces
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This document provides an overview of interfaces and namespaces in C#. It defines interfaces as a syntactic contract that classes inherit from to define common properties, methods, and events, while classes implement the specific functionality. Namespaces are used to avoid naming conflicts by logically grouping classes. Namespaces can be defined using the namespace keyword and items within a namespace can be accessed by prepending the namespace name or using the using keyword to import namespace names. Nested namespaces can also be defined.
Learn C# programming - Interfaces & Namespaces
- 1. Learn C# Programming Interfaces & Namespaces Eng Teong Cheah MVP Visual Studio & Development Technologies
- 2. Interfaces
- 3. Interfaces An interface is defined as a syntactical contract that all the classes inheriting the interface should follow. The interface defines the ‘what’ part of the syntactical contract and the deriving classes define the ‘how’ party of the syntactical contract. Interfaces defines properties, methods, and events, which are the members of the interface. Interfaces contain only the declaration of the members. It is the responsibility f the deriving class to define the members. It often helps in providing a standard structure that the deriving classes would follow. Abstract classes to some extent serve the same purpose, however, they are mostly used when only few methods are to be declared by the base class and the deriving class implements the functionalities.
- 4. Declaring Interfaces Interfaces are declared using the interface keyword. It is similar to class declaration. Interface statements are public by default.
- 6. Namespaces
- 7. Namespaces A namespace is designed for providing a way to keep one set of names separate from another. The class names declared in one namespace does not conflict with the same class names declared in another.
- 8. Defining a Namespace A namespace definition begins with the keyword namespace followed by the namespace name as follows – namespace namespace_name { // code declarations } To call the namespace-enabled version of either function or variable, prepend the namespace name as follows- namespace_name.item_name;
- 9. Demo – Defining a Namespace
- 10. The using Keyword The using keyword states that the program is using the names in the given namespace. For example, we are using the System namespace in our programs. The class Console is defined there. We just write – Console.WriteLine ("Hello there");
- 11. The using Keyword We could have written the fully qualified name as - Console.WriteLine ("Hello there"); You can also avoid prepending of namespaces with the using namespace directive. This directive tells the compiler that the subsequent code is making use of names in the specified namespace.
- 12. Demo – The using keyword
- 13. Nested Namespaces You can define one namespace inside another namespace as follows – namespace namespace_name1 { // code declarations namespace namespace_name2 { // code declarations } }
- 16. Thank you