Python中的意外列表行为 [英] Unexpected list behavior in Python

问题描述

我想撤消一个列表，但是我设法做到了，但是在工作的中间我发现了一些奇怪的事情.以下程序正常运行，但 list_reversed [i] = list [len(list)-1-i] 和 print(list [i])当然，最后一行)会导致列表中的更改.我没看到什么?我的Python版本是3.3.3.预先谢谢你.

I wanted to reverse a list, and I managed to do so, but in the middle of the work I noticed something strange. The following program works as expected but uncommeting line list_reversed[i]=list[len(list)-1-i] and print(list[i]) (commenting the last line of course) leads to a change in list. What am I not seeing? My Python version is 3.3.3. Thank you in advance.

list=[1,2,3,4,5,6]

list_reversed=list

for i in range(0,len(list)):

    #list_reversed[i]=list[len(list)-1-i]
    #print(list[i])

    print(list[len(list)-1-i])

推荐答案

以下内容:

list_reversed = list 

使两个变量引用相同的列表.当您更改一个时，它们都会更改.

makes the two variables refer to the same list. When you change one, they both change.

要复制，请使用

list_reversed = list[:]

最好还是使用内置函数，而不要编写自己的函数:

Better still, use the builtin function instead of writing your own:

list_reversed = reversed(list)

P.S.我建议不要使用list作为变量名，因为它会掩盖内置.

P.S. I'd recommend against using list as a variable name, since it shadows the builtin.

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