yield return的用法简介

使用yield return 语句可一次返回一个元素。

   迭代器的声明必须满足以下要求：

• IEnumerator<T>。

yield return 语句中的表达式  　　类型隐式转换为泛型类型参数。

yield break 语句：

• 
  

• 包含不安全的块的方法。

public class Student
    {
        public String Name { get; set; }
        public int Age { get; set; }
        //代码更简洁
        public IEnumerable<Student> Students
        {
            get
            {
                yield return new Student { Name = "Tadpole", Age = 400 };
                yield return new Student { Name = "Pinwheel", Age = 25 };
                yield return new Student { Name = "Milky Way", Age = 0 };
                yield return new Student { Name = "Andromeda", Age = 3 };
            }
        }
 
        public IEnumerable<Student> Students2
        {
            get
            {
                List<Student> list = new List<Student>();
                list.Add(new Student { Name = "Tadpole", Age = 400 });
                list.Add(new Student { Name = "Tadpole", Age = 400 });
                list.Add(new Student { Name = "Tadpole", Age = 400 });
                list.Add(new Student { Name = "Tadpole", Age = 400 });
                list.Add(new Student { Name = "Tadpole", Age = 400 });
                return list;
            }
        }
    }

    //将不会返回空   
     public static IEnumerable<string> Test()
        {
            yield break;
        }