1. 切片
>>> '123456'[1:4]
'234'
>>> [1,2,3,4,56,6][1:4]
[2, 3, 4]
>>> (1,2,3,4,5,6,7)[1:4]
(2, 3, 4)
2. 长度len()
>>> len('123456')
6
>>> len([1,2,3,4])
4
>>> len((1,2,3,4,56,3))
6
3. 比较大小max()、min()
>>> max([1,2,3,4,67,9])
67
>>> min([1,2,3,4,67,9])
1
>>> max('Hello World')
'r'
>>> min('Hello World')
' '
>>> min('HelloWOrld')
'H'
>>> max((1,2,3,4,56))
56
>>> min((1,2,3,4,5,6))
1
注意：字符串比较大小，比较的是ascll码,python中查看ascll采用的是
ord()方法>>> ord('H') 72 >>> ord(' ') 32 >>> ord('r') 114
