python中a=x和a=x[:]有什么区别 [英] what is the difference between a = x and a=x[:] in python

问题描述

我正在尝试学习 Python.有人可以帮助我理解以下两者之间的区别:a = x vs a=x[:]

I am trying to learn Python. Can someone please help me understand the difference between following two: a = x vs a=x[:]

推荐答案

a = x 创建引用:

a = [2]
x = a
print id(a)
print id(x)

产生:

39727240
39727240

所以如果你改变 a 那么 x 也会改变，因为它们是相同的对象

So if you alter a then x would change too because they are the same objects

鉴于

a = x[:] 创建一个新对象

a = [2]
x = a[:]
print id(a)
print id(x)

产生:

41331528
39722056

但是在这里改变 a 不会改变 x 因为它们是不同的对象

But over here changing a doesn't alter x because they are different objects

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