{"id":1420,"date":"2023-04-07T21:55:08","date_gmt":"2023-04-07T14:55:08","guid":{"rendered":"https:\/\/csharptutorial.net\/?page_id=1420"},"modified":"2023-04-07T21:55:10","modified_gmt":"2023-04-07T14:55:10","slug":"csharp-method-group-conversion-to-delegate","status":"publish","type":"page","link":"https:\/\/www.csharptutorial.net\/csharp-tutorial\/csharp-method-group-conversion-to-delegate\/","title":{"rendered":"C# Method Group Conversion to Delegate"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about C# method group and how the method group conversion to delegate process works.<\/p>\n\n\n\n

What is a method group in C#<\/h2>\n\n\n\n

In C#, a method group is a set of overloaded methods that share the same name but have different parameter lists. When referring to a method by its name without specifying its parameters, you are referring to the method group.<\/p>\n\n\n\n

For example, the following Calculator<\/code> class has two Add<\/code> methods with different parameter types:<\/p>\n\n\n

class<\/span> Calculator<\/span>\n{\n    public<\/span> static<\/span> int<\/span> Add<\/span>(int<\/span> a, int<\/span> b<\/span>)<\/span> => a + b;\n    public<\/span> static<\/span> double<\/span> Add<\/span>(double<\/span> a, double<\/span> b<\/span>)<\/span> => a + b;\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
When you refer to the Add<\/code> method without specifying its arguments, you’re referring to the Add<\/code> method group.<\/p>\n\n\n\n
Method group conversion to delegate<\/h2>\n\n\n\n
In C#, a method group conversion to delegate<\/a> is the process of converting a method group into a delegate type. <\/p>\n\n\n\n
A delegate is a type that represents a reference to a method with a specified signature. By using a delegate, you can invoke a method or pass the method reference as an argument to other methods.<\/p>\n\n\n\n
When you use a method group in a context that requires a delegate, the C# compiler automatically performs the method group conversion to delegate. <\/p>\n\n\n\n
For example, you can assign a method group to a delegate variable like this:<\/p>\n\n\n
class<\/span> Calculator<\/span>\n{\n    public<\/span> static<\/span> int<\/span> Add<\/span>(int<\/span> a, int<\/span> b<\/span>)<\/span> => a + b;\n    public<\/span> static<\/span> double<\/span> Add<\/span>(double<\/span> a, double<\/span> b<\/span>)<\/span> => a + b;\n}\n\n\nclass<\/span> Program<\/span>\n{\n    delegate<\/span> int<\/span> Calculate<\/span>(int<\/span> a, int<\/span> b<\/span>)<\/span>;\n\n    public<\/span> static<\/span> void<\/span> Main<\/span>(string<\/span>[] args<\/span>)<\/span>\n    {\n        Calculate cal = Calculator.Add;\n        var<\/span> result = cal(10<\/span>, 20<\/span>);\n\n        Console.WriteLine(result);\n    }\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, the Add<\/code> method group is converted to the Calculate<\/code> delegate type, which has the same signature as the Calculate<\/code> method. This allows you to assign the method reference to a delegate variable cal<\/code>, which can then be invoked with a string argument.<\/p>\n\n\n\n
Note that the method group conversion to delegate is only allowed when the method group has a single best match for the delegate’s signature. If you have multiple methods in the group that could match the delegate signature, C# will issue an error.<\/p>\n\n\n\n
Improved Method group conversion to delegate in C# 11<\/h2>\n\n\n\n
The following example demonstrates the improved method group conversion to delegate feature introduced in C# 11:<\/p>\n\n\n
using<\/span> static<\/span> System.Console;\n\nclass<\/span> Calculator<\/span>\n{\n    public<\/span> static<\/span> int<\/span> Add<\/span>(int<\/span> a, int<\/span> b<\/span>)<\/span> => a + b;\n    public<\/span> static<\/span> double<\/span> Add<\/span>(double<\/span> a, double<\/span> b<\/span>)<\/span> => a + b;\n}\n\nclass<\/span> Program<\/span>\n{\n    static<\/span> int<\/span> Calculate<\/span>(int<\/span> x, int<\/span> y, Func<int<\/span>, int<\/span>, int<\/span>> f<\/span>)<\/span> => f(x, y);\n\n    public<\/span> static<\/span> void<\/span> Main<\/span>(string<\/span>[] args<\/span>)<\/span>\n    {\n        int<\/span> x = 20<\/span>, \n            y = 10<\/span>;\n        \n        var<\/span> result = Calculate(x, y, Calculator.Add);\n        \n        WriteLine(result); \/\/ 30<\/span>\n    }\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
30<\/code><\/span><\/pre>\n\n\n
In this example instead of passing a lambda expression to the Calculate()<\/code> method:<\/p>\n\n\n
var<\/span> result = Calculate(x, y, (x,y) => Calculator.Add(x,y));<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
 you can pass a method group to it:<\/p>\n\n\n
var<\/span> result = Calculate(x, y, Calculator.Add);<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
Behind the scenes, the C# compiler converts the method group to the delegate that accepts two integers and returns an integer.<\/p>\n\n\n\n
Summary<\/h2>\n\n\n\n
    \n
  • A method group is a collection of methods that have the same name but different parameters.<\/li>\n\n\n\n
  • Method group conversion to delegate is the process of automatically converting a method group into a delegate type that can be used to reference a method with a matching signature.<\/li>\n<\/ul>\n
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