yield return 语句返回集合的一个元素

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yield break 可停止迭代
------------------------------------------------------------------Student.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApplication3
{
public class Student
{
string[] str = new string[] { "张飞", "关羽", "贝贝", "香香" };
///
/// 正序迭代
///
///
public IEnumerator GetEnumerator()
{
for (int i = 0; i < str.Length; i++)
{
yield return str[i];
}
}
///
/// 倒序迭代
///
///
public IEnumerable Reverse()
{
for (int i = str.Length-1; i >= 0; i--)
{
yield return str[i];
}
}
///
/// 自定义迭代
///
/// 开始索引
/// 长度
///
public IEnumerable Subset(int index, int length)
{
for (int i = index; i < index+length; i++)
{
yield return str[i];
}
}
}
} ------------------------------------------------------------------主程序
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApplication3
{
class Program
{
static void Main(string[] args)
{
Student s = new Student();
foreach (var item in s)//正序迭代
{
Console.WriteLine(item);
}
Console.WriteLine("reverse");
foreach (var item in s.Reverse())//倒序迭代
{
Console.WriteLine(item);
}
Console.WriteLine("subset");//自定义迭代
foreach (var item in s.Subset(1,1))
{
Console.WriteLine(item);
}
Console.ReadKey();
}
}
}