C # Extension methods

Demo Code:

public class program    {        static void Main (string[] args)        {            var txt = "Hello";            Console.WriteLine (txt. GetString ());            var inttxt = "123";            Console.WriteLine (Inttxt. GetInt ());            var inttxt1 = "ASD";            Console.WriteLine (Inttxt1. GetInt ());            Console.WriteLine ("234". GetInt ());            Console.WriteLine ("Qwe"). GetInt ());        }    }    public static class exstring    {public        static string GetString (this string source)        {            return source + " Extension method ";        }        public static int GetInt (this string source)        {            var outint = 0;            if (!string. IsNullOrEmpty (source))            {                var result = Int. TryParse (Source,out outint);                return outint;            }            return outint;        }    }

Code output:

Description

1. Extension methods are static methods that belong to static classes

2, the first parameter of the This keyword, parameter type is the type that needs to be extended

C # Extension methods