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This article introduces the relevant knowledge of "how to realize the Func delegation of C#". In the operation of the actual case, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

What is Func entrustment

A Func delegate represents a delegate with a return type

II. Definition of Func delegation

View the definition of Func:

Using System.Runtime.CompilerServices;namespace System {/ Summary: / / encapsulates a method that takes two parameters and returns a value of the type specified by the TResult parameter. / / parameter: / / arg1: / / the first parameter of the method encapsulated by this delegate. / arg2: / / the second parameter of the method encapsulated by this delegate. / / Type parameter: / / T1: / / the type of the first parameter of the method encapsulated by this delegate. / T2: / / the type of the second parameter of the method encapsulated by this delegate. / TResult: / / the return value type of the method encapsulated by this delegate. / return result: / / the return value of the method encapsulated by this delegate. [TypeForwardedFrom ("System.Core, Version=3.5.0.0, Culture=Neutral, PublicKeyToken=b77a5c561934e089")] public delegate TResult Func (T1 arg1, T2 arg2);}

You will find that Func is actually a delegate with multiple output parameters and a return value.

3. Example

Func has at least 0 input parameters and up to 16 input parameters, which are returned generically according to the return value. There must be a return value, not void.

Func indicates that there are no input parameters, and the return value is a delegate of type int.

Func indicates that the input parameter is object and string, and the return value is a delegate of type int.

Func indicates that the input parameter is object and string, and the return value is a delegate of type int.

Func indicates that the passed-in parameter is T1MageT2recoveryT3 (generic), and the return value is a delegate of type int.

The code example is as follows:

Using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace FunDemo {class Program {static void Main (string [] args) {/ / has no parameters, as long as the return value Func fun1 = new Func (FunWithNoPara); int result1= fun1 (); Console.WriteLine (result1) Console.WriteLine ("- -"); Func fun2 = delegate {return 19;}; int result2 = fun2 (); Console.WriteLine (result2); Console.WriteLine ("- -") Func fun3 = () = > {return 3;}; int result3 = fun3 (); Console.WriteLine (result3); Console.WriteLine ("- -"); / / there is a parameter and a return value Func fun4 = new Func (FunWithPara) Int result4 = fun4 (4); Console.WriteLine ($"here is a method with a parameter and a return value, and the return value is: {result4}"); Console.WriteLine ("- -"); / / use delegate Func fun5 = delegate (int I) {return i.ToString () }; string result5 = fun5 (5); Console.WriteLine ($"here is a delegate of a parameter and a return value, and the return value is: {result5}"); Console.WriteLine ("- -") / / use anonymous delegate Func fun6 = (int I) = > {return i.ToString ();}; string result6 = fun6 (6); Console.WriteLine ($"here is an anonymous delegate with a parameter and a return value, and the return value is: {result6}") Console.WriteLine ("- -"); / / multiple input parameters Func fun7 = new Func (FunWithMultiPara); bool result7 = fun7 (2, "2"); Console.WriteLine ($"here is the method with multiple input parameters, and the return value is: {result7}") Console.WriteLine ("- -"); / / use delegate Func fun8 = delegate (int I, string s) {return i.ToString () .Equals (s)? True: false;}; bool result8 = fun8 (2, "abc"); Console.WriteLine ($"here is the delegate with multiple input parameters, and the return value is: {result8}"); Console.WriteLine ("-") / / use anonymous delegate Func fun9 = (int I, string s) = > {return i.ToString () .Equals (s)? True: false;}; bool result9 = fun9 (45, "ert"); Console.WriteLine ($"here is an anonymous delegate with multiple input parameters, and the return value is: {result9}"); Console.ReadKey ();} static int FunWithNoPara () {return 10 } static int FunWithPara (int I) {return I;} static bool FunWithMultiPara (int iJing string s) {return i.ToString () .Equals (s)? True: false;}

Running result:

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