python核心编程----读书笔记

1，is , == 的区别

a is b：指的是a和b指向内存的同一空间；a == b：指的是a和b所指向的值是相等的。直接上代码

>>> a = [1,2,3]
>>> b = [1,2,3]
>>> c = a
>>> a == b
True
>>> a == c
True
>>> a is b
False
>>> a is c
True

2，copy与deepcopy的区别

a = b是浅拷贝，浅拷贝不会另外的将内容拷贝一份，只是类似于指向复制，深拷贝是完完全复制出来。

>>> a = [1,2,3]
>>> b = [4,5,6]
>>> c = [a,b]
>>> import copy
>>> d = copy.copy(c)
>>> id(c)
5697224
>>> id(d)
47890312
>>> id(c[0])
47968456
>>> id(d[0])
47968456
>>> e = copy.deepcopy(c)
>>> id(e)
45702920
>>> id(e[0])
45715592

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