python数据类型可变与不可变深入分析

>>> x = 18
>>> id(x)
4497811200
>>> id(18)
4497811200
>>> x = 19 
>>> id(x)
4497811232
>>> id(18)
4497811200
>>> y = 18
>>> id(y)
4497811200
>>>

>>> x = [1,2,3]
>>> id(x)
4501838920
>>> y = [1,2,3]
>>> z = [1,2,3]
>>> id(y)
4501838600
>>> id(z)
4501838664

#a的值改变了，a对应的内存地址也改变了
>>> a=1
>>> id(a)
4497810656
>>> a = 2
>>> id(2)
4497810688
#直接对a操作，相当于拷贝了一份a的值，在其他内存地址操作，a的值不变
>>> a+1
3
>>> id(a)
4497810688
>>> a
2
#b的值改变了,b对应的内存地址不变，第一次给b赋值的时候，给b划分一块内存空间，该空间就不变了
>>> b = [1,2,3]
>>> id(b)
4501839496
#直接对b操作，b的值改变，b指向的内存空间不变
>>> b.append(4)
>>> id(b)
4501839496
>>> b
[1, 2, 3, 4]
>>>

#整型
a = 1
print(id(a), type(a))
a = 2
print(id(a), type(a))
# 4361254304 <class 'int'>
# 4361254336 <class 'int'>
#字符串
b = 'anne'
print(id(b),type(b))
b = 'anne1995'
print(id(b),type(b))
# 4363638744 <class 'str'>
# 4363684784 <class 'str'>
#元组
c1 = ['1','2']
c = (1,2,c1)
print(c,id(c),type(c))
c1[1] = 'djx'
print(c,id(c),type(c))
# (1, 2, ['1', '2']) 4363948248 <class 'tuple'>
# (1, 2, ['1', 'djx']) 4363948248 <class 'tuple'>

#集合
s = {1, 'd', '34', '1', 1}
print(s, type(s), id(s))
s.add('djx')
print(s, type(s), id(s))
# {1, '1', 'd', '34'} <class 'set'> 4401385256
# {1, '1', '34', 'd', 'djx'} <class 'set'> 4401385256
#列表
list = [1,'q','qwer',True]
print(list,type(list),id(list))
list.append('djx')
print(list,type(list),id(list))
# [1, 'q', 'qwer', True] <class 'list'> 4401113608
# [1, 'q', 'qwer', True, 'djx'] <class 'list'> 4401113608
#字典
tuple = (1)
dic = {1:2}
d = { tuple:1,'key2':'djx','key3':'li'}
print(d,type(d),id(d))
d['key4'] = 'haha'
print(d,type(d),id(d))
# {1: 1, 'key2': 'djx', 'key3': 'li'} <class 'dict'> 4401075976
# {1: 1, 'key2': 'djx', 'key3': 'li', 'key4': 'haha'} <class 'dict'> 4401075976