今天的学习课程阶数了c#语言的基础部分。最后一天的课程主要讲了不常用的枚举类型，还有，递归。

一。枚举类型

 //枚举类型定义

        //不定义之前，第一个索引是默认从0开始，。往后一次加一。

        //若之前定义的一个字段的索引指向了之后的某个默认字段。他俩完全相同

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using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace 枚举类型_递归

{

    class Program

    {

 enum meiju : int

        {

            one,

            two,

            three,

            four = three

        }

主函数内写

 //不取int的时候出来的是常量字段

            Console.WriteLine(meiju.one);

            //int时表示。出来这个字段代表的值

            Console.WriteLine((int)meiju.one);

            //若定义枚举类型时，下面有个字段等于之前的字段。那么就是等于之前的字段

            Console.WriteLine(meiju.four);

            //若等于之前的一个常量字段时候强制取int。那就等于之前的那个字段

            Console.WriteLine((int)meiju.four);

            //第一个常量若从1开始，之后的常量的索引值会自动加1

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二。递归

递归类似于循环都是一些比较有规律的问题

下面。我们来看一道比较典型的例题

例一

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace

{

    class Program

    {

public int Jie(int a)

        {

           int s;

            if (a == 1)

           {

                return a;

           }

           return

           s = a * Jie(a - 1);

        }

主函数内写

Program hs=new Program();

         int b=hs.Jie(5);//表示从1 乘到5

         Console.WriteLine(b);

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例二

猴子吃桃子每天吃掉昨天的三分之二还多一个。求刚开始猴子有多少桃子(//后面是for循环做的相同题目对比)

                                                                                   

                                                                                                       //int s = 2;

                                                                                                          //for (int i = 1; i < 9; i++)

                                                                                                          //{

                                                                                                         //    s = (s + 1) * 3;

                                                                                                          //}

                                                                                                        //Console.WriteLine(s);

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using System; 

using System.Collections.Generic;                                                             

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace

{

    class Program

    {

public double tao(int a)

        {

           double s;

            if (a == 9)

           {

                return 2;

            }

            return

                s =  (tao(a+1)+1)*3;

        }

主函数内写

Program hs = new Program();

   double b = hs.tao(1);//表示求到第一天

   Console.WriteLine(b);

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