列舉相信大家都不陌生，今天又再看了下感覺有了新的收穫。下面記錄自己的程式碼：

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace EnumberOption
{
    /// <summary>
    /// 宣告一個列舉類
    /// </summary>
    public class MyIEnumberator
    {
        /// <summary>
        /// 迭代器返回列舉數
        /// </summary>
        public MyYield mcyield=new MyYield();
    }

    /// <summary>
    /// 非泛型介面列舉數
    /// </summary>
    public class ColorEnumberator : IEnumerator
    {
        string[] Colors;//實現IEnumberator
        /// <summary>
        /// 索引位置
        /// </summary>
        int Postion = -1;
        /// <summary>
        /// 當前元素
        /// </summary>
        public object Current
        {
            get
            {
                if (Postion == -1)
                {
                    throw new InvalidOperationException();
                }
                if (Postion == Colors.Length)
                {
                    throw new InvalidOperationException();
                }
                return Colors[Postion];
            }
        }

        /// <summary>
        /// 移動到下一個元素
        /// </summary>
        /// <returns></returns>
        public bool MoveNext()
        {
            if (Postion < Colors.Length - 1)
            {
                Postion++;
                return true;
            }
            else
            {
                return false;
            }
        }

        /// <summary>
        /// 重置
        /// </summary>
        public void Reset()
        {
            Postion = -1;
        }

        /// <summary>
        /// 建構函式
        /// </summary>
        /// <param name="theColors"></param>
        public ColorEnumberator(string[] theColors)
        {
            Colors = new string[theColors.Length];
            for (int i = 0; i < theColors.Length; i++)
            {
                Colors[i] = theColors[i];
            }
        }
    }

    /// <summary>
    /// 泛型列舉數介面實現ColorEnumerator
    /// </summary>
    public class ColorEnumberatorList : IEnumerator<String>
    {
        string[] Colors;
        int Position = -1;
        /// <summary>
        /// 當前元素 泛型
        /// </summary>
        public string Current
        {
            get
            {
                return Colors[Position];
            }
        }

        /// <summary>
        /// 顯示實現Current 非泛型
        /// </summary>
        object IEnumerator.Current
        {
            get { return Colors[Position];}
        }

        /// <summary>
        /// 移動到下一個
        /// </summary>
        /// <returns></returns>
        public bool MoveNext()
        {
            if (Position < Colors.Length - 1)
            {
                Position++;
                return true;
            }
            else
            {
                return false;
            }
        }

        /// <summary>
        /// 重置
        /// </summary>
        public void Reset()
        {
            Position = -1;
        }

        /// <summary>
        /// 銷燬操作
        /// </summary>
        public void Dispose()
        {
        }

        /// <summary>
        /// 建構函式
        /// </summary>
        /// <param name="theColors"></param>
        public ColorEnumberatorList(string[] theColors)
        {
            Colors = new string[theColors.Length];
            for (int i = 0; i < theColors.Length; i++)
            {
                Colors[i] = theColors[i];
            }
        }
    }
}
 

using EnumberOption;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ImageBookCode.Enumerator
{
    /// <summary>
    /// 非泛型實現
    /// </summary>
    public class MyColors:IEnumerable
    {
        string[] Colors ;

        /// <summary>
        /// ColorEnumberator實現了IEnumerator
        /// </summary>
        /// <returns></returns>
        public IEnumerator GetEnumerator()
        {
            return new ColorEnumberator(Colors);
        }

        /// <summary>
        /// 建構函式
        /// </summary>
        /// <param name="theColors"></param>
        public MyColors(string[] theColors)
        {
            Colors = new string[theColors.Length];
            for (int i = 0; i < theColors.Length; i++)
            {
                Colors[i] = theColors[i];
            }
        }

        /// <summary>
        /// 無參建構函式
        /// </summary>
        public MyColors()
        {
            Colors = new string[3];
            Colors[0] = "Red";
            Colors[1] = "Yellow";
            Colors[2] = "Blue";
        }
    }

    /// <summary>
    /// 泛型實現
    /// </summary>
    public class MyColorsList : IEnumerable<string>
    {
        string[] Colors = { "Red", "Yellow", "Blue" };
        /// <summary>
        /// IEnumerable<T>版本"
        /// </summary>
        /// <returns></returns>
        public IEnumerator<string> GetEnumerator()
        {
            return new ColorEnumberatorList(Colors);
        }

        /// <summary>
        /// 顯示實現 IEnumerable版本
        /// </summary>
        /// <returns></returns>
        IEnumerator IEnumerable.GetEnumerator()
        {
            return new ColorEnumberatorList(Colors);
        }
    }
}
 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace EnumberOption
{
    /// <summary>
    /// 使用迭代器
    /// </summary>
    public class MyYield
    {
        /// <summary>
        /// 返回列舉數
        /// </summary>
        /// <returns></returns>
        public IEnumerator<string> GetEnumerator()
        {
            ////返回列舉數
            return BlackAndWhite();
        }

        /// <summary>
        /// 迭代器
        /// </summary>
        /// <returns></returns>
        public IEnumerator<string> BlackAndWhite()
        {
            yield return "black";
            yield return "gray";
            yield return "white";
        }
    }
}
 

using EnumberOption;
using ImageBookCode.Enumerator;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ImageBookCode
{
    class Program
    {
        static void Main(string[] args)
        {
            ////實現介面的列舉數
            MyColors mc = new MyColors();
            foreach (var item in mc)
            {
                Console.WriteLine(item);
            }
            ////使用泛型介面實現的列舉數
            MyColorsList mcl = new MyColorsList();
            foreach (var color in mcl)
            {
                Console.WriteLine(color);
            }
            ////使用迭代器返回列舉數
            MyIEnumberator IEnumberColorYield = new MyIEnumberator();
            foreach (var itemIEnum in IEnumberColorYield.mcyield)
            {
                Console.WriteLine(itemIEnum);
            }
            Console.ReadKey();
        }
    }
}

程式碼打包下載點選這裡 開發環境：VS2013