{"id":361,"date":"2022-01-05T15:17:44","date_gmt":"2022-01-05T08:17:44","guid":{"rendered":"https:\/\/csharptutorial.net\/?page_id=361"},"modified":"2022-06-03T08:12:44","modified_gmt":"2022-06-03T01:12:44","slug":"csharp-inheritance","status":"publish","type":"page","link":"https:\/\/www.csharptutorial.net\/csharp-tutorial\/csharp-inheritance\/","title":{"rendered":"C# Inheritance"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about C# inheritance that allows a class to reuse the properties and methods of another class.<\/p>\n\n\n\n

Introduction to the C# inheritance<\/h2>\n\n\n\n

Inheritance is one of the core concepts in object-oriented programming. Inheritance allows a class<\/a> to inherit from another class. <\/p>\n\n\n\n

Inheriting from a class allows you to reuse the functionality of the class instead of building it from scratch.<\/p>\n\n\n\n

C# allows a class to inherit only from a single class. This is called single inheritance. C# doesn’t support multiple inheritances where a class can inherit from two or more classes.<\/p>\n\n\n\n

Suppose you have a Person<\/code> class with properties FirstName<\/code>, LastName<\/code>, Age<\/code>, and FullName<\/code> and a method Introduce()<\/code>:<\/p>\n\n\n

\/\/ Person.cs<\/span>\nclass<\/span> Person<\/span>\n{\n    public<\/span> string<\/span> FirstName { get<\/span>; set<\/span>; }\n\n    public<\/span> string<\/span> LastName { get<\/span>; set<\/span>; }\n\n    public<\/span> byte<\/span> Age { get<\/span>; set<\/span>; }\n\n    public<\/span> string<\/span> FullName => $\"{FirstName}<\/span> {LastName}<\/span>\"<\/span>;\n\n    public<\/span> string<\/span> Introduce<\/span>(<\/span>)<\/span> => $\"Hi, I'm {FullName}<\/span>.\"<\/span>;\n    \n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
And you want to define an Employee<\/code> class that has all the properties as the Person<\/code> class and two more properties JobTitle<\/code> and Salary<\/code>.<\/p>\n\n\n\n
Instead of copying code from the Employee<\/code> class to the Employee<\/code> class, you can use inheritance. The following defines the Employee<\/code> class that inherits from the Person<\/code> class:<\/p>\n\n\n
\/\/ Employee.cs<\/span>\n\nclass<\/span> Employee<\/span>: Person<\/span>\n{\n    \n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example: <\/p>\n\n\n\n
  • The Person<\/code> class is called the parent<\/strong> class, a base<\/strong> class, or a super<\/strong> class <\/li>
  • The Employee<\/code> class is called a child <\/strong>class, derived class, or subclass<\/strong>.<\/li><\/ul>\n\n\n\n
    We also say that the Employee<\/code> class extends the Person<\/code> class.  <\/p>\n\n\n\n
    Since the Employee<\/code> class inherits the properties and methods of the Person<\/code> class, its objects behave like objects of the Person<\/code> class. For example:<\/p>\n\n\n
    \/\/ Program.cs<\/span>\n\nvar<\/span> employee = new<\/span> Employee\n{\n    FirstName = \"John\"<\/span>,\n    LastName = \"Doe\"<\/span>,\n    Age = 25<\/span>\n};\n\nConsole.WriteLine(employee.Introduce());<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
    Output:<\/p>\n\n\n
    Hi, I'm John Doe.<\/span><\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
    As you can see, the Employee<\/code> behaves like the Person<\/code> class without duplicating the code. We say that an employee is a person. And the inheritance models an is-a<\/strong> relationship.<\/p>\n\n\n\n
    Extending a parent class<\/h2>\n\n\n\n
    The following adds the JobTitle<\/code> and Salary<\/code> properties to the Employee<\/code> class:<\/p>\n\n\n
    \/\/ Employee.cs<\/span>\nclass<\/span> Employee<\/span> : Person<\/span>\n{\n    public<\/span> string<\/span> JobTitle { get<\/span>; set<\/span>; }\n    public<\/span> decimal<\/span> Salary { get<\/span>; set<\/span>; }\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
    Now, the Employee<\/code> class has its own properties and the inherited properties from the Person<\/code> class. The following creates a new instance of the Employee<\/code> class with all the properties:<\/p>\n\n\n
    \/\/ Program.cs<\/span>\n\nvar<\/span> employee = new<\/span> Employee\n{\n    FirstName = \"John\"<\/span>,\n    LastName = \"Doe\"<\/span>,\n    Age = 25<\/span>,\n    JobTitle = \"C# Developer\"<\/span>,\n    Salary = 120000<\/span>\n};\n\nConsole.WriteLine(employee.Introduce());<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
    Output:<\/p>\n\n\n
    Hi, I'm John Doe.<\/span><\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
    Summary<\/h2>\n\n\n\n
    • Inheritance allows a class (subclass) to inherit from another class (base class) to extend or customize the base class.<\/li>
    • C# allows a class to inherit from a single class. This is called the single inheritance.<\/li><\/ul>\n
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