{"id":9080,"date":"2025-03-06T13:21:46","date_gmt":"2025-03-06T13:21:46","guid":{"rendered":"http:\/\/localhost:8080\/csharp-test\/docs\/csharp\/polymorphism\/polymorphism-with-interfaces\/"},"modified":"2025-03-26T03:48:09","modified_gmt":"2025-03-26T03:48:09","slug":"polymorphism-with-interfaces","status":"publish","type":"docs","link":"https:\/\/www.completecsharptutorial.com\/docs\/csharp\/polymorphism\/polymorphism-with-interfaces\/","title":{"rendered":"Polymorphism with Interfaces"},"content":{"rendered":"\t\t
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Mastering Polymorphism with Interfaces in C#<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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\ud83d\ude80 Introduction<\/h4>\n

Hey there, future C# pro! \ud83c\udfaf Have you ever wondered how different classes can share a common behavior while implementing their own unique way of doing things? That\u2019s where Polymorphism with Interfaces in C#<\/strong> comes in!<\/p>\n

Imagine you\u2019re playing a video game. You press the same “Jump” button, but different characters (a human, a robot, or a bird) jump in their own unique ways. That\u2019s polymorphism in action! \ud83c\udfae<\/p>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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\r\n <\/i>\r\n
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\ud83d\udcda What You Are Going to Learn in This Lesson<\/h5>\r\n

\u2714\ufe0f What is Polymorphism with Interfaces in C#<\/strong>?
\u2714\ufe0f Why do we need it?
\u2714\ufe0f Syntax and explanation \ud83d\udcdd
\u2714\ufe0f Hands-on coding examples \ud83d\udcbb
\u2714\ufe0f A real-world example to make it crystal clear \ud83c\udf0e
\u2714\ufe0f Common mistakes and best practices \ud83c\udfc6<\/p> <\/div>\r\n <\/div>\r\n \r\n \r\n \r\n \t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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\ud83e\uddd0 What is Polymorphism with Interfaces in C#?<\/h3>

Polymorphism means “many forms.”<\/strong> When a class implements an interface, it provides its own version of the methods declared in that interface.<\/p>

An interface only defines what<\/strong> needs to be done, but the class decides how<\/strong> to do it!<\/p>

\u00a0<\/p>

\u2753 Why is Polymorphism with Interfaces in C# Important?<\/h3>

\u2705 Encourages code reusability<\/strong>
\u2705 Supports multiple inheritance<\/strong> (since a class can implement multiple interfaces)
\u2705 Makes code flexible and scalable<\/strong>
\u2705 Helps decouple<\/strong> code for better maintainability<\/p>

\u00a0<\/h4>

\ud83d\udccc Syntax of Interfaces in C#<\/h4>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\r\n\t\t\t\t\r\n\t\t\t\t\tinterface IAnimal  \r\n{  \r\n    void MakeSound();  \/\/ Method without implementation\r\n}  \r\n\r\nclass Dog : IAnimal  \r\n{  \r\n    public void MakeSound()  \r\n    {  \r\n        Console.WriteLine("Dog says: Woof! \ud83d\udc36");  \r\n    }  \r\n}  \r\n\r\nclass Cat : IAnimal  \r\n{  \r\n    public void MakeSound()  \r\n    {  \r\n        Console.WriteLine("Cat says: Meow! \ud83d\udc31");  \r\n    }  \r\n}  \r\n\t\t\t\t<\/code>\r\n\t\t\t<\/pre>\r\n            <\/div>\r\n                \t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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\ud83d\udcbb Example 1: Basic Polymorphism with Interfaces<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\r\n\t\t\t\t\r\n\t\t\t\t\tusing System;\r\n\r\ninterface IShape\r\n{\r\n    void Draw();\r\n}\r\n\r\nclass Circle : IShape\r\n{\r\n    public void Draw()\r\n    {\r\n        Console.WriteLine("Drawing a Circle \ud83d\udfe2");\r\n    }\r\n}\r\n\r\nclass Square : IShape\r\n{\r\n    public void Draw()\r\n    {\r\n        Console.WriteLine("Drawing a Square \ud83d\udfe5");\r\n    }\r\n}\r\n\r\nclass Program\r\n{\r\n    static void Main()\r\n    {\r\n        IShape shape1 = new Circle();\r\n        IShape shape2 = new Square();\r\n\r\n        shape1.Draw();\r\n        shape2.Draw();\r\n    }\r\n}\r\n\t\t\t\t<\/code>\r\n\t\t\t<\/pre>\r\n            <\/div>\r\n                \t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\ud83c\udfc6 Output:<\/h5>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\r\n\t\t\t\t\r\n\t\t\t\t\tDrawing a Circle \ud83d\udfe2  \r\nDrawing a Square \ud83d\udfe5  \r\n\t\t\t\t<\/code>\r\n\t\t\t<\/pre>\r\n            <\/div>\r\n                \t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\ud83d\udd0d Explanation<\/h4>
  • IShape<\/strong> is an interface that defines a method Draw()<\/code>.<\/li>
  • Circle<\/strong> and Square<\/strong> classes implement the interface and provide their own versions of Draw()<\/code>.<\/li>
  • In Main()<\/code>, we use polymorphism by assigning objects of Circle<\/code> and Square<\/code> to the IShape<\/code> type.<\/li>
  • When we call Draw()<\/code>, it executes the method specific to the actual object.<\/li><\/ul>
    \u00a0<\/h3>
    \ud83c\udf0d Real-World Example: Payment System<\/h3>
    Imagine an online shopping website<\/strong> \ud83d\uded2. Users can pay with a credit card, PayPal, or cryptocurrency<\/strong>. Each payment method follows the same process but has different implementations.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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    \r\n\t\t\t\t\r\n\t\t\t\t\tusing System;\r\n\r\ninterface IPayment\r\n{\r\n    void ProcessPayment(double amount);\r\n}\r\n\r\nclass CreditCard : IPayment\r\n{\r\n    public void ProcessPayment(double amount)\r\n    {\r\n        Console.WriteLine($"Processing Credit Card Payment of ${amount} \ud83d\udcb3");\r\n    }\r\n}\r\n\r\nclass PayPal : IPayment\r\n{\r\n    public void ProcessPayment(double amount)\r\n    {\r\n        Console.WriteLine($"Processing PayPal Payment of ${amount} \ud83c\udd7f\ufe0f");\r\n    }\r\n}\r\n\r\nclass Bitcoin : IPayment\r\n{\r\n    public void ProcessPayment(double amount)\r\n    {\r\n        Console.WriteLine($"Processing Bitcoin Payment of ${amount} \u20bf");\r\n    }\r\n}\r\n\r\nclass Program\r\n{\r\n    static void Main()\r\n    {\r\n        IPayment paymentMethod;\r\n\r\n        paymentMethod = new CreditCard();\r\n        paymentMethod.ProcessPayment(100);\r\n\r\n        paymentMethod = new PayPal();\r\n        paymentMethod.ProcessPayment(50);\r\n\r\n        paymentMethod = new Bitcoin();\r\n        paymentMethod.ProcessPayment(200);\r\n    }\r\n}\r\n\t\t\t\t<\/code>\r\n\t\t\t<\/pre>\r\n            <\/div>\r\n                \t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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    \ud83c\udfc6 Output:<\/h5>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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    \r\n\t\t\t\t\r\n\t\t\t\t\tProcessing Credit Card Payment of $100 \ud83d\udcb3  \r\nProcessing PayPal Payment of $50 \ud83c\udd7f\ufe0f  \r\nProcessing Bitcoin Payment of $200 \u20bf  \r\n\t\t\t\t<\/code>\r\n\t\t\t<\/pre>\r\n            <\/div>\r\n                \t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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    \ud83d\udd0d Explanation<\/h4>
    • IPayment<\/code> defines a ProcessPayment()<\/code> method.<\/li>
    • CreditCard<\/code>, PayPal<\/code>, and Bitcoin<\/code> implement IPayment<\/code> in different ways.<\/li>
    • In Main()<\/code>, we assign different payment methods to the IPayment<\/code> type and call ProcessPayment()<\/code>.<\/li>
    • The correct method runs based on the actual object.<\/li><\/ul>
      \u00a0<\/h3>
      \u26a0\ufe0f Common Mistakes and Best Practices<\/h3>
      \u274c Mistake:<\/strong> Forgetting to implement all methods from an interface.
      \u2705 Fix:<\/strong> Always provide implementations for all interface methods.<\/p>
      \u274c Mistake:<\/strong> Trying to create an object of an interface.
      \u2705 Fix:<\/strong> You cannot<\/strong> instantiate an interface directly. Use a class that implements it.<\/p>
      \u00a0<\/h3>
      \ud83c\udfaf Conclusion<\/h3>
      You did it! \ud83c\udf89 Now you understand Polymorphism with Interfaces in C#<\/strong> and why it\u2019s so powerful. Interfaces allow us to enforce a contract in different classes while enabling flexibility. Whether it\u2019s drawing shapes, processing payments, or handling game characters, interfaces make it easy to achieve polymorphism<\/strong>.<\/p>
      \ud83d\udc49 Keep practicing! Try creating your own interfaces and implementing them in different ways.<\/p>
      \u00a0<\/h3>
      \u23ed\ufe0f Next What?<\/h3>
      In the next chapter<\/strong>, you will learn Polymorphism with Abstract Classes in C#<\/strong>. It’s going to be another fun ride! Stay tuned. \ud83d\ude80<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"
      Learn Polymorphism with Interfaces in C# with real-world examples, code, and explanations. Understand why it’s important and how to use it effectively.<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":6255,"menu_order":162,"comment_status":"open","ping_status":"closed","template":"","doc_tag":[],"class_list":["post-9080","docs","type-docs","status-publish","hentry","no-post-thumbnail"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.completecsharptutorial.com\/wp-json\/wp\/v2\/docs\/9080","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.completecsharptutorial.com\/wp-json\/wp\/v2\/docs"}],"about":[{"href":"https:\/\/www.completecsharptutorial.com\/wp-json\/wp\/v2\/types\/docs"}],"author":[{"embeddable":true,"href":"https:\/\/www.completecsharptutorial.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.completecsharptutorial.com\/wp-json\/wp\/v2\/comments?post=9080"}],"version-history":[{"count":4,"href":"https:\/\/www.completecsharptutorial.com\/wp-json\/wp\/v2\/docs\/9080\/revisions"}],"predecessor-version":[{"id":9087,"href":"https:\/\/www.completecsharptutorial.com\/wp-json\/wp\/v2\/docs\/9080\/revisions\/9087"}],"up":[{"embeddable":true,"href":"https:\/\/www.completecsharptutorial.com\/wp-json\/wp\/v2\/docs\/6255"}],"wp:attachment":[{"href":"https:\/\/www.completecsharptutorial.com\/wp-json\/wp\/v2\/media?parent=9080"}],"wp:term":[{"taxonomy":"doc_tag","embeddable":true,"href":"https:\/\/www.completecsharptutorial.com\/wp-json\/wp\/v2\/doc_tag?post=9080"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}