A[1:3]          取出1到3，都是正数的情况下，缺填的为0（第一个），end（最后一个）B[-3:]           取出倒数第三个到倒数第一个，都是负数的情况下，缺填的为-1（最后一个）C[1:10:2]     从1到10，每2个取一个

>>> d = {'a': 1, 'b': 2, 'c': 3}
>>> for key in d:
...     print(key)
...
a
c
b

for value in d.values()

for k, v in d.items()

>>> from collections import Iterable
>>> isinstance('abc', Iterable) # str是否可迭代
True
>>> isinstance([1,2,3], Iterable) # list是否可迭代
True
>>> isinstance(123, Iterable) # 整数是否可迭代
False

>>> for i, value in enumerate(['A', 'B', 'C']):
...     print(i, value)
...
0 A
1 B
2 C

>>> list(range(1, 11))
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

>>> [x * x for x in range(1, 11)]
[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

>>> [m + n for m in 'ABC' for n in 'XYZ']
['AX', 'AY', 'AZ', 'BX', 'BY', 'BZ', 'CX', 'CY', 'CZ']

>>> d = {'x': 'A', 'y': 'B', 'z': 'C' }
>>> [k + '=' + v for k, v in d.items()]
['y=B', 'x=A', 'z=C']

>>> [x * x for x in range(1, 11) if x % 2 == 0]
[4, 16, 36, 64, 100]

>>> L = [x * x for x in range(10)]
>>> L
[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
>>> g = (x * x for x in range(10))
>>> g
<generator object <genexpr> at 0x1022ef630>

>>> next(g)
0
>>> next(g)
1
>>> next(g)
4
>>> next(g)
9
>>> next(g)
16
>>> next(g)
25
>>> next(g)
36
>>> next(g)
49
>>> next(g)
64
>>> next(g)
81
>>> next(g)
Traceback (most recent call last):File "<stdin>", line 1, in <module>
StopIteration

>>> g = (x * x for x in range(10))
>>> for n in g:
...     print(n)
...
0
1
4
9
16
25
36
49
64
81

def fib(max):n, a, b = 0, 0, 1while n < max:print(b)a, b = b, a + bn = n + 1return 'done'

def fib(max):n, a, b = 0, 0, 1while n < max:yield ba, b = b, a + bn = n + 1return 'done'

def triangles():L = [1]while True:yield LL.append(0)L = [L[i - 1] + L[i] for i in range(len(L))]

n = 0
for t in triangles():print(t)n = n + 1if n == 10:break

>>> from collections import Iterable
>>> isinstance([], Iterable)
True
>>> isinstance({}, Iterable)
True
>>> isinstance('abc', Iterable)
True
>>> isinstance((x for x in range(10)), Iterable)
True
>>> isinstance(100, Iterable)
False

>>> from collections import Iterator
>>> isinstance((x for x in range(10)), Iterator)
True
>>> isinstance([], Iterator)
False
>>> isinstance({}, Iterator)
False
>>> isinstance('abc', Iterator)
False

>>> isinstance(iter([]), Iterator)
True
>>> isinstance(iter('abc'), Iterator)
True

for x in [1, 2, 3, 4, 5]:pass

# 首先获得Iterator对象:
it = iter([1, 2, 3, 4, 5])
# 循环:
while True:try:# 获得下一个值:x = next(it)except StopIteration:# 遇到StopIteration就退出循环break