C ＃ [advanced chapter] C ＃ anonymous method [lambda expression to be supplemented...]

C# Learning summary - General catalogue

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Preface

We have already mentioned , A delegate is used to refer to a method that has the same label as it . let me put it another way , You can use a delegate object to call methods that can be referenced by a delegate .

Anonymous methods （Anonymous methods） Provides a The technique of passing code blocks as delegate parameters . The anonymous method is A method with no name but a body .

In anonymous methods, you You do not need to specify a return type , It's from within the method body return The sentence infers .

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Syntax for writing anonymous methods

The anonymous method is by using 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); yes The body of an anonymous method .

Delegates can be called through anonymous methods , You can also call , namely , By passing method parameters to the delegate object .

Be careful : The body of an anonymous method needs a ;.

for example ：

nc(10);

example

The following example demonstrates the concept of anonymous methods ：

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)
        {
    
            //【01】 Create delegate instances using anonymous methods 
            NumberChanger nc = delegate (int x)
            {
    
                Console.WriteLine("Anonymous Method: {0}", x);
            };
            // 【01】 Using delegates to call anonymous methods 
            nc(10);

            // 【02】 Instantiate the delegate using the name 
            nc = new NumberChanger(AddNum);
            // 【02】 Using delegates to call named methods 
            nc(5);

            // 【03】 Instantiate the delegate using another naming method 
            nc = new NumberChanger(MultNum);
            // 【03】 Using delegates to call named methods 
            nc(2);
            Console.ReadKey();
        }
    }
}

Running results ：

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

summary

• About anonymous methods ： It will be used in practice , And can understand the code written by others .

C# Learning summary - General catalogue