整形:(不可变类型)
>>> a = 123
>>> type(a)
<class 'int'>
长整形:(在python3中已经废弃了)
>>> a = 123L
>>> type(a)
<type 'long'>
浮点型:
>>> c = 1.2
>>> type(c)
<class 'float'>
在python3和python2中,进行的运算之后的结果,首先默认会向参加运算的复杂类型靠拢
在python3中,除法的结果会自动向浮点数靠拢
>>> a = 1.0
>>> b = 5
>>> c = b / a
>>> type(c)
<class 'float'>
布尔型:
True :非0 、非空
False: 0
字符型:
>>> a = "xiaofan"
>>> type(a)
<class 'str'>
单引号和双引号用法上几乎是没有区别的,注意在多引号使用时的场景
>>> a = "It's a boy"
三引号:(输出的字符串是可以换行的)
>>> info = """my name is xiaofan
... I'm a boy """
>>> info
"my name is xiaofan\nI'm a boy "
>>> print(info)
my name is xiaofan
I'm a boy
转义:\ 或 r (注意\不能再字符串的最后面出现)
>>> a = "\b"
>>> print(a)
>>> a = "\\b"
>>> print(a)
\b
>>> a = r"\b"
>>> print(a)
\b
索引的切片:
>>> name = "xiaofan"
>>> name[0]
'x'
>>> name[1]
'i'
>>> name[-1]
'n'
>>> name[0:4]
'xiao'
字符串是不可变类型 不能修改里面的值
name[1]=a
会报错
字符串拼接:
>>> name = "xiaofan"
>>> name + name
'xiaofanxiaofan'
字符串相乘:
>>> name * 3
'xiaofanxiaofanxiaofan'
列表:list
列表的索引:
>>> list1 = [1,2,3,['a',"b"],"c"]
>>> list1[0]
1
>>> list1[3][1]
'b'
>>> list1[3:5]
[['a', 'b'], 'c']
>>> list1[:]
[1, 2, 3, ['a', 'b'], 'c']
复杂列表取值:
list2=[1,2,3,4,5,6,7,8,[1,[3,[4,[5,[6,7,],7,],7,],8,],7,9],0,8]
如果取到其中的值:
>>> list2[-3]
[1, [3, [4, [5, [6, 7], 7], 7], 8], 7, 9]
>>> list2[-3][-3]
[3, [4, [5, [6, 7], 7], 7], 8]
>>> list2[-3][-3][-2]
[4, [5, [6, 7], 7], 7]
>>> list2[-3][-3][-2][-2]
[5, [6, 7], 7]
>>> list2[-3][-3][-2][-2][-2]
[6, 7]
修改列表的值:
>>> list1
[1, 2, 3, ['a', 'b'], 'c']
>>> list1[3][0]="xiaofan"
>>> list1
[1, 2, 3, ['xiaofan', 'b'], 'c']
修改列表内存地址不会改变:(列表是一个可变对象)
>>> list1=[1,2,3,4]
>>> id(list1)
140228069335304
>>> list1[1]="t"
>>> list1
[1, 't', 3, 4]
>>> id(list1)
140228069335304
元祖:tuple
>>> tuple1=(1,3,5,[1,3,6],"a",('a','b'))
>>> type(tuple1)
<class 'tuple'>
>>> tuple1[0]
1
>>> tuple1[-1]
('a', 'b')
元祖是不可以修改的(如果元祖里面有可变类型可以修改其中的内容)
>>> tuple1[3][0]='a'
元祖、列表转换:
>>> tuple1
(1, 3, 5, ['a', 3, 6], 'a', ('a', 'b'))
>>> list1=list(tuple1)
>>> list1
[1, 3, 5, ['a', 3, 6], 'a', ('a', 'b')]
>>> tuple(list1)
(1, 3, 5, ['a', 3, 6], 'a', ('a', 'b'))
del删除变量:
>>> list=1
>>> type(list)
<class 'int'>
>>> del list
>>> list
<class 'list'>
变量的引用计数:
>>> import sys
>>> num = 100
>>> sys.getrefcount(num)
7
引用计数为0时变量被删除