python day3

Posted 2020-09-20

1、数值拷贝

import copy
# ######数字、字符串######
n1 = 123
print(id(n1))
n2 = n1
print(id(n2))

###浅拷贝###
n2 = copy.copy(n1)
print(id(n2))

###深拷贝###
n3 = copy.deepcopy(n1)
print(id(n3))

C:\Users\811314\AppData\Local\Programs\Python\Python35-32\python.exe C:/homework/day3/1.py
492322480
492322480
492322480
492322480

Process finished with exit code 0

2、字符串

import copy
# ######数字、字符串######
n1 = "my name is hellworld"
print(id(n1))
n2 = n1
print(id(n2))

###浅拷贝###
n2 = copy.copy(n1)
print(id(n2))

###深拷贝###
n3 = copy.deepcopy(n1)
print(id(n3))

C:\Users\811314\AppData\Local\Programs\Python\Python35-32\python.exe C:/homework/day3/1.py
5973920
5973920
5973920
5973920

Process finished with exit code 0

import copy
# ######数字、字符串######
n1 = ["helloworld","hapen"]
print(id(n1))
n2 = n1
print(id(n2))

###浅拷贝###
n2 = copy.copy(n1)
print(id(n2))

###深拷贝###
n3 = copy.deepcopy(n1)
print(id(n3))

C:\Users\811314\AppData\Local\Programs\Python\Python35-32\python.exe C:/homework/day3/1.py
12817912
12817912
10370784
12816672

Process finished with exit code 0

对于 数字 和 字符串 而言，赋值、浅拷贝和深拷贝无意义，因为其永远指向同一个内存地址。

 浅拷贝，在内存中只额外创建第一层数据

深拷贝，在内存中将所有的数据重新创建一份（排除最后一层，即：python内部对字符串和数字的优化