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This article introduces the knowledge of "how to use Lambda expressions in C#". Many people will encounter this dilemma in the operation of actual cases, 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!

I. introduction

1. "Lambda expression" is a special anonymous function, which simplifies the use of anonymous delegate and is an efficient expression similar to functional programming. Lambda simplifies the amount of code that needs to be written in development.

2. It can contain expressions and statements, and can be used to create delegate or expression directory tree types, supporting inline expressions with input parameters that can be bound to a delegate or expression tree.

3. All Lambda expressions use the Lambda operator = >, which is pronounced "goes to". On the left side of the Lambda operator are input parameters, if any, and on the right are expressions or statement blocks. The Lambda expression x = > x * x is pronounced "x goes to x times x".

4. Lambda expression syntax:

No parameter: () = > expr

One parameter: param= > expr

Multiple parameters: (param-list) = > expr

Note: if there is only one sentence of code in the method, you can omit the code block symbol, that is, you don't have to write {}

2. For example: 1. Entrusting example method / / entrusting supermarket shopping delegate int GuangChaoshi (int a); static void Main (string [] args) {GuangChaoshi gwl = JieZhang; Console.WriteLine (gwl (10) + "); / / printing 20, commissioned application Console.ReadKey () } / / check out public static int JieZhang (int a) {return a + 10;} 2, lambda expression / / entrust delegate int GuangChaoshi (int a); static void Main (string [] args) {/ / GuangChaoshi gwl = JieZhang; GuangChaoshi gwl = p = > p + 10 Console.WriteLine (gwl (10) + "); / / print 20, the application of the expression Console.ReadKey ();} 3, multi-parameter / / entrust supermarket shopping delegate int GuangChaoshi (int apenint b); static void Main (string [] args) {GuangChaoshi gwl = (pjingz) = > z-(p + 10) Console.WriteLine (gwl (10100) + "); / / print the parameter a Console.ReadKey () corresponding to the parameter bline p of 80 public string Name z; 3. Built-in delegate 1, set operation public class Person {public string Name {get;set;} public int Age {get;set }} class Program {public static List PersonsList () {List persons = new List (); for (int I = 0; I

< 7; i++) { Person p = new Person() { Name = i + "儿子", Age = 8 - i, }; persons.Add(p); } return persons; } static void Main(string[] args) { List persons = PersonsList(); persons = persons.Where(p =>

P.Age > 6) .ToList (); / / set of all Person with Age > 6 Person per = persons.SingleOrDefault (p = > p.Age = = 1); / / single people class of Age=1 persons = persons.Where (p = > p.Name.Contains ("son")) .ToList () / / all Name sets containing son's Person} 2, Func delegated static void Main (string [] args) {Func gwl = (p, j) = > {if (p + j = = 10) {return true } return false;}; Console.WriteLine (gwl (5Magne5) + ""); / / print 'True',z corresponding parameter bjournal p corresponding parameter a Console.ReadKey () Fourth, lambda expression tree dynamic creation method static void Main (string [] args) {/ / i*j+w*x ParameterExpression a = Expression.Parameter (typeof (int), "I"); / / create a parameter in the expression tree, as a node, here is the lowest node ParameterExpression b = Expression.Parameter (typeof (int), "j") BinaryExpression be = Expression.Multiply (int b); / / here iQuij, a node in the expression tree, ParameterExpression c = Expression.Parameter (typeof (int), "w"); ParameterExpression d = Expression.Parameter (typeof (int), "x"); BinaryExpression be1 = Expression.Multiply (c, d) BinaryExpression su = Expression.Add (be,be1); / / operate two intermediate nodes to produce the endpoint Expression lambda = Expression.Lambda (su,a,b,c,d); Console.WriteLine (lambda + "") / / print'(iGramj) + (wrecox)', z corresponds to the parameter b Func p corresponds to the parameter a Func f = lambda.Compile (); / / compiles the lambda expression described by the expression tree into executable code and generates a delegate for the lambda expression Console.WriteLine (f (1,1,1,1) + "); / / print 2 Console.ReadKey ();}" how to use Lambda expressions in C# "is introduced here, thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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