Python的五个标准数据类型你认识几个

>>> num1 = 1
>>> num2 = 2
>>>

>>> num1 = 1
>>> num2 = 2
>>> del num1
>>> print(num1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'num1' is not defined
删除对象，意味着已经从内从中剔除，就不能继续使用，否则报错

>>> str = 'sssss'
>>> str1 = "ssssss"
>>> print(str, str1)
sssss ssssss
>>> str
'sssss'
>>> str1
'ssssss'
注意在使用交互式编译器下不用print强格式输出，就会默认使用单引号，表示此为字符串

 例：
 str = 'abcdef'
 str[:2]+str[2:]其实就是一个与str相同内容的字符串
 str[0:2]的结果为'ab',也就是前包后不包
 str[-2:-1]
 此处：
 >>> str[-2:-1]
'e' //此处引证前包后不包
>>> str[-1]
'f' //切片或引用都可为负，0与-0都是左侧第一个字母，右侧首位为-1开始，超出下标一般会报错，但在python中做过处理，出界时返回空字符
>>>

>>> str1 = 'a'
>>> str2 = 'b'
>>> str1 + str2
'ab'
>>> str1+'b'
'ab'
>>> 'xs'+'xsx'
'xsxsx'
>>>

>>> 'a''b'
'ab'
>>>

>>> str = 'c'
>>> str'd'
  File "<stdin>", line 1
    str'd'
         ^
SyntaxError: invalid syntax
>>>

>>> str = 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa'
'bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb'
>>> str
'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb'
>>>

>>> 4*'str'
'strstrstrstr'
>>> 'str'*4
'strstrstrstr'
>>>

>>> list = [1,2,3,4,5,'s',3.4]
>>> list[5]
's'
>>> list[0:2]
[1, 2]
>>> list[-3:-1]
[5, 's']
>>>
>>> list*2
[1, 2, 3, 4, 5, 's', 3.4, 1, 2, 3, 4, 5, 's', 3.4]
>>> list2 = ['s',22222,87.3]
>>>list+list2
[1, 2, 3, 4, 5, 's', 3.4, 's', 22222, 87.3]

>>> list.append(34)
>>> print(list)
[1, 2, 3, 4, 5, 's', 3.4, 34]

>>> st1 = [1,2,3]
>>> st2 = [1.2,1.3,2.3]
>>> st3 = ['a','b','c']
>>> st = [st1,st2,st3]
>>> st
[[1, 2, 3], [1.2, 1.3, 2.3], ['a', 'b', 'c']]

>>> st
[[1, 2, 3], [1.2, 1.3, 2.3], ['a', 'b', 'c']]
>>> del st[0]
>>> st
[[1.2, 1.3, 2.3], ['a', 'b', 'c']]
>>> st[0:1] = []
>>> st
[['a', 'b', 'c']]
>>>

>>> stu = (1,2,3,4,5)
>>> stu1 = 1,2,3,4,5
>>> stu
(1, 2, 3, 4, 5)
>>> stu1
(1, 2, 3, 4, 5)
>>>

>>> stu = (1,2,3,4,5)
>>> stu1 = 1,2,3,4,5
>>> stu
(1, 2, 3, 4, 5)
>>> stu1
(1, 2, 3, 4, 5)
>>> stu[0] = 110
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment
>>> stu*2
(1, 2, 3, 4, 5, 1, 2, 3, 4, 5)
>>> stu[0]
1
>>> stu[0:1]
(1,)
>>>

>>> student1 = {'name':'zxb','sex':'man','age':'12'}
>>> student1
{'name': 'zxb', 'sex': 'man', 'age': '12'}
>>>

>>> student1['age']
'12'
>>>student1.keys()
dict_keys(['name', 'sex', 'age'])
>>> student1.values()
dict_values(['zxb', 'man', '12'])
>>>

>>> sorted(student1)
['age', 'name', 'sex']