Python基础学习 -- 迭代器

a=[1,2,3,4,5]
it =iter(a)
print(next(it))
print(next(it))
运行结果：
1
2

class diedaiqi():
    def __init__(self,s,t):
        self.s=s
        self.t=t
    def __iter__(self):
        return self#返回迭代器对象，固定写法
    def __next__(self):
        if self.s>self.t:
            raise StopIteration
        it=self.s**2
        self.s+=1
        return it
a=diedaiqi(9,20)
for i in a:
    print(i)