迭代器斐波那契数列

 1 class Num:
 2     total1 = 0
 3 
 4     def __init__(self, num, num1):
 5         self.num = num
 6         self.num1 = num1
 7 
 8     def __iter__(self):
 9         return self
10 
11     def __next__(self):
12         if self.num>100:
13             raise StopIteration('终止了')
14         self.num,self.num1 = self.num1,self.num+self.num1
15         return self.num
16 n1 = Num(1,2)
17 # for i in n1:
18 #     print(i)
19 print(n1.__next__())
20 print(n1.__next__())
21 print(n1.__next__())
22 print(n1.__next__())
23 print(n1.__next__())
24 print(n1.__next__())
25 print(n1.__next__())
26 print(n1.__next__())
27 print(n1.__next__())
28 print(n1.__next__())
29 print(n1.__next__())
30 输出：
31 2
32 3
33 5
34 8
35 13
36 21
37 34
38 55
39 89
40 144
41 Traceback (most recent call last):
42   File "C:/Users/Administrator/Desktop/python/3月9日/斐波那契数列.py", line 29, in <module>
43     print(n1.__next__())
44   File "C:/Users/Administrator/Desktop/python/3月9日/斐波那契数列.py", line 13, in __next__
45     raise StopIteration('终止了')
46 StopIteration: 终止了

斐波那契数列   可以用交换元素直接进行处理   a,b = b,a+b