【学习整理】循环、列表

while:
    循环体

for 目标 in 表达式：
    循环体

favourite = 'fish'
for i in favourite:
    print(i,end=' ')
输出：f i s h　

member = [11,'cat',3.14]
for i in member:
    print(i,end=' ')
输出：11 cat 3.14

test=['cat','你好呀','he']
for i in test:
    print(i,len(i))
输出：cat 3
你好呀 3
he 2

for i in range(0,20,2):
    print(i)	
输出：0
2
4
6
8
10
12
14
16
18

for i in range(10):
    if i%2 != 0:
        continue
    i += 2
    print(i,end=' ')

>>> member
[88, 90, 100, 65, 70]
>>> member[0:2]  //第一个值是开始的位置，第二个值是结束的位置但不包含他 2-0=2 列出两个元素
[88, 90]
>>> member[:2]
[88, 90]
>>> member[3:]
[65, 70]

>>> member
[88, 90, 100, 65, 70]
>>> member2 = member  //将member的地址给member2，会互相影响
>>> member3 = member[:]   //创建新的地址
>>> member.pop()
70
>>> member2
[88, 90, 100, 65]
>>> member3
[88, 90, 100, 65, 70]

>>> old = [1,2,3,4,5]
>>> old1 = old
>>> old2 = old[:]
>>> old.append(6)
>>> old1
[1, 2, 3, 4, 5, 6]
>>> old2
[1, 2, 3, 4, 5]
>>> old = [6]
>>> old1
[1, 2, 3, 4, 5, 6]
>>> old2
[1, 2, 3, 4, 5]

>>> list3 * 3
[111, 111, '123', 111, 111, '123', 111, 111, '123']
>>> list3*=3
>>> list3
[111, 111, '123', 111, 111, '123', 111, 111, '123']

>>> test = [x*3 for x in range(0,10,2)]
>>> test
[0, 6, 12, 18, 24]

>>> list4 = [123,['a','b']]
>>> 'a' in list4[1]
True

>>> list4 = [123,['a','b']]
>>> list4[1][1]
'b'

>>> list3

[111, 111, '123', 111, 111, '123', 111, 111, '123']

>>> list3.count(111)

6

>>> list3.count('123')

3

>>> list3.index(111)
0
>>> list3.index(111,3,5)  //第2、3个参数表范围
3

>>> list4

[123, ['a', 'b']]

>>> list4.reverse()

>>> list4

[['a', 'b'], 123]

>>> list6 = [5,3,2,5,7,1]
>>> list6.sort()
>>> list6
[1, 2, 3, 5, 5, 7]
>>> list6.sort(reverse=True) //逆序