{"id":645,"date":"2022-05-08T14:55:28","date_gmt":"2022-05-08T07:55:28","guid":{"rendered":"https:\/\/csharptutorial.net\/?page_id=645"},"modified":"2022-12-30T09:39:00","modified_gmt":"2022-12-30T02:39:00","slug":"csharp-anonymous-methods","status":"publish","type":"page","link":"https:\/\/www.csharptutorial.net\/csharp-tutorial\/csharp-anonymous-methods\/","title":{"rendered":"C# Anonymous Methods"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about C# anonymous methods which are methods without names.<\/p>\n\n\n\n

Introduction to C# anonymous methods<\/h2>\n\n\n\n

When assigning a method to a delegate<\/a>, you define a method, either instance method or static method<\/a>, and then assign it to the delegate. For example:<\/p>\n\n\n

class<\/span> Program<\/span>\n{\n    delegate<\/span> int<\/span> Transfomer<\/span>(int<\/span> x<\/span>)<\/span>;\n    static<\/span> int<\/span> Square<\/span>(int<\/span> x<\/span>)<\/span>\n    {\n        return<\/span> x * x;\n    }\n    public<\/span> static<\/span> void<\/span> Main<\/span>(string<\/span>[] args<\/span>)<\/span>\n    {\n        Transfomer transform = Square;\n\n        Console.WriteLine(transform(10<\/span>)); \/\/ 100<\/span>\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
First, declare a delegate called Transformer<\/code> that accepts an integer and returns an integer:<\/p>\n\n\n
delegate<\/span> int<\/span> Transfomer<\/span>(int<\/span> x<\/span>)<\/span>;<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Second, define a static method called Square()<\/code> with the same signature as the Transformer<\/code> delegate:<\/p>\n\n\n
static<\/span> int<\/span> Square<\/span>(int<\/span> x<\/span>)<\/span>\n{\n    return<\/span> x * x;\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Third, assign the Square<\/code> method to the Transformer<\/code> delegate and invoke it inside the Main()<\/code> method:<\/p>\n\n\n
Transfomer transform = Square;\nConsole.WriteLine(transform(10<\/span>)); \/\/ 100<\/span><\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Sometimes, defining a new method is not necessary because you only use it once. It creates unwanted overhead. <\/p>\n\n\n\n
An anonymous method uses the delegate<\/code> keyword followed by an optional parameter declaration and method body. For example:<\/p>\n\n\n
\nclass<\/span> Program<\/span>\n{\n    delegate<\/span> int<\/span> Transfomer<\/span>(int<\/span> x<\/span>)<\/span>;\n\n    public<\/span> static<\/span> void<\/span> Main<\/span>(string<\/span>[] args<\/span>)<\/span>\n    {\n        Transfomer transform = delegate<\/span> (int<\/span> x) { return<\/span> x * x; };\n\n        Console.WriteLine(transform(10<\/span>)); \/\/ 100<\/span>\n    }\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, we don’t define the static method Square<\/code>. Instead, we assign an anonymous method to the transform<\/code> delegate.<\/p>\n\n\n\n
The following statement defines an anonymous method and assigns it to the Transformer<\/code> delegate:<\/p>\n\n\n
delegate<\/span> (int<\/span> x) { return<\/span> x * x; }<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Anonymous methods can access the outer variables. For example:<\/p>\n\n\n
\nclass<\/span> Program<\/span>\n{\n    delegate<\/span> decimal<\/span> Pricing<\/span>(decimal<\/span> price<\/span>)<\/span>;\n\n    public<\/span> static<\/span> void<\/span> Main<\/span>(string<\/span>[] args<\/span>)<\/span>\n    {\n        decimal<\/span> tax = 0.08<\/span>m;\n        decimal<\/span> price = 100<\/span>m;\n\n        Pricing calculateNet = delegate<\/span>(decimal<\/span> price) {\n            return<\/span> price * (1<\/span> + tax);\n        };\n\n        Console.WriteLine(calculateNet(price));\n    }\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
108<\/span><\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, the anonymous method accesses the tax<\/code> variable from the Main()<\/code> method.<\/p>\n\n\n\n
Starting from C# 3, you can use lambda expressions instead of anonymous methods, which have more concise syntax.<\/p>\n\n\n\n
Summary<\/h2>\n\n\n\n
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  • Anonymous methods are methods without names.<\/li>\n\n\n\n
  • Use the delegate<\/code> keyword to define an anonymous method.<\/li>\n<\/ul>\n
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C# allows you to create a delegate and immediately assign a code block to it. This code block can be either an anonymous method or a lambda expression<\/a>.<\/p>\n\n\n\n