1.61. C# anonymous method

We have already mentioned that delegates are used to reference methods that have the same label as them. In other words, you can use a delegate object to call a method that can be referenced by a delegate.

Anonymous methods provide a technique for passing code blocks as delegate parameters. An anonymous method is a method that has no name but only a principal.

You do not need to specify a return type in an anonymous method, it is derived from the return statement inferred.

1.61.1. Write the syntax for anonymous methods #

Anonymous methods are done by using the delegate keyword to create a delegate instance to declare. For example:

delegate void NumberChanger(int n); ... NumberChanger nc = delegate(int x) { Console.WriteLine("Anonymous Method: {0}", x); }; 

Code block Console.WriteLine("Anonymous Method: {0}", x); is the bodyof an anonymous method.

A delegate can be called either through an anonymous method or through a named method call, that is, by passing method parameters to the delegate object.

Note: the body of an anonymous method needs a ; .

For example:

nc(10); 

1.61.2. Example #

The following example demonstrates the concept of anonymous methods:

Example #

using System; delegate void NumberChanger(int n); namespace DelegateAppl { class TestDelegate { static int num = 10; public static void AddNum(int p) { num += p; Console.WriteLine("Named Method: {0}", num); } public static void MultNum(int q) { num *= q; Console.WriteLine("Named Method: {0}", num); } static void Main(string[] args) { // Creating a delegate instance using anonymous methods NumberChanger nc = delegate(int x) { Console.WriteLine("Anonymous Method: {0}", x); }; // Using anonymous methods to call delegates nc(10); // Instantiating delegates using naming methods nc = new NumberChanger(AddNum); // Calling delegates using named methods nc(5); // Instantiating a delegate using another naming method nc = new NumberChanger(MultNum); // Calling delegates using named methods nc(2); Console.ReadKey(); } } } 

When the above code is compiled and executed, it produces the following results:

Anonymous Method: 10 Named Method: 15 Named Method: 30 