索引器

索引器

没有名字 ,索引器的内部本质（ILSpy的IL模式下看）类型this[参数]{get;set;}

可以是只读或者只写（在get或者set前加上private）

字符串是只读索引，因此不能对字符串中的某个字符进行从新赋值，即只能char ch = s[5];不能s[5]=‘a’。

开发中自己写的机会很少，一道面试题：C#中索引器是否只能根据数字进行索引？是否允许多个索引器参数？答案：可以进行非数字索引，可以允许多个参数进行索引

using System;

usingSystem.Collections;

usingSystem.Collections.Generic;

usingSystem.Linq;

usingSystem.Text;

usingSystem.Threading.Tasks;

namespaceTestConsole

{

   class Program

   {

        static void Main(string[] args)

        {

            MyIntIndex myIntIndex = newTestConsole.MyIntIndex();//整型索引

            stringname1 = myIntIndex[1];

            Console.WriteLine(name1);

            Hashtable ht = new Hashtable();

            ht.Add("001", "chizi");

            ht.Add("002", "dandan");

            MyStringIndex myStringIndex = newTestConsole.MyStringIndex(ht);//字符串索引

            string name2 = myStringIndex["001"];

            Console.WriteLine(name2);

            Console.ReadKey();

        }

   }

   class MyStringIndex

   {

        private Hashtable ht;//字符串索引用到哈希表来存放键值对

        public MyStringIndex(Hashtableht)

        {

            this.ht = ht;

        }

        public string this[stringkey]

        {

            get

            {

                string name =(string)ht[key];

                returnname;

            }

            set

            {

                ht[key] =value;

            }

        }

   }

   class MyIntIndex

   {

        private static string[] name = { "dandan", "chizi", "jianguo"};

        public string this[intindex]

        {

            get

            {

                stringn = name[index];

                returnn;

            }

            set

            {

                name[index] =value;

            }

        }

   }

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