这是怎么回事?

tgctg2020

>>> n=list(range(10))
>>> n
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> i=enumerate(n)
>>> list(i)
[(0, 0), (1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6), (7, 7), (8, 8), (9, 9)]
>>> reversed(list(i))
<list_reverseiterator object at 0x000001ED5850E248>
>>> list(reversed(list(1)))
Traceback (most recent call last):
  File "<pyshell#5>", line 1, in <module>
    list(reversed(list(1)))
TypeError: 'int' object is not iterable
>>> list(i)
[]
>>>


为什么list(reversed(list(1)))会报错?为什么list(i)的值会变成[]???

小伤口

enumerate()遍历数据，同时输出数据与索引
类似于for循环，只是遍历
遍历一次之后自然为空

>>> n=list(range(10))
>>> n
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> i=enumerate(n)
>>> list(i)
[(0, 0), (1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6), (7, 7), (8, 8), (9, 9)]
>>> list(i)
[]
>>> for i in range(5):
        print(i)

        
0
1
2
3
4
>>> print(i)
4
>>> 

而你报错的原因是list(reversed(list(1)))
里面是i不是1

list(reversed(list(i)))
[(9, 9), (8, 8), (7, 7), (6, 6), (5, 5), (4, 4), (3, 3), (2, 2), (1, 1), (0, 0)]

要想保存数据应该提前赋值

>>> i=enumerate(n)
>>> a=list(i)
>>> a
[(0, 0), (1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6), (7, 7), (8, 8), (9, 9)]
>>> a
[(0, 0), (1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6), (7, 7), (8, 8), (9, 9)]
>>> 

jackz007

        这一句写错了吧

ist(reversed(list(1)))

        应该是下面这样才对

list(reversed(list(i)))