Yield Return 和 Yield Break 的出现是为了简化迭代器。

类如果能被遍历则必须有IEnumerator<string> GetEnumerator() 方法， 并有用Yield Return

方法如果能被遍历则返回类型为 IEnumerable<string>，并有用Yield Return

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace TestYield{    class Program    {        static void Main(string[] args)        {            foreach (string v in new Animal())            {                Console.WriteLine(v);            }            foreach (string v in getList())            {                Console.WriteLine(v);            }            Console.ReadLine();        }        static IEnumerable<string> getList()        {            yield return "cccc";            yield return "dddd";        }          }    public class Animal {       //类迭代必须要有的方法,使用Yield简化了迭代的实现      public IEnumerator<string> GetEnumerator()        {            yield return "aaaaa";            yield return "bbbbb";        }    }}

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

namespace TestYield
{
    class Program
    {
        static void Main(string[] args)
        {

            foreach (string v in new Animal())
            {
                Console.WriteLine(v);
            }


            foreach (string v in getList())
            {
                Console.WriteLine(v);
            }
            Console.ReadLine();
        }


        static IEnumerable<string> getList()
        {
            yield return "cccc";
            yield return "dddd";
        }
      
    }


    public class Animal {

      public IEnumerator<string> GetEnumerator()
        {
            yield return "aaaaa";
            yield return "bbbbb";
        }

    }
}

C#中YieldReturn的用法