为什么slice [:-0]在Python中返回空列表 [英] Why does slice [:-0] return empty list in Python

问题描述

今天在编写一些单元测试时偶然发现了一些令人困惑的东西:

Stumbled upon something slightly perplexing today while writing some unittests:

blah = ['a', 'b', 'c']
blah[:-3] # []
blah[:-2] # ['a']
blah[:-1] # ['a', 'b']
blah[:-0] # []

我一辈子都无法弄清楚为什么blah[:-0] # []应该是这种情况，该模式似乎似乎暗示它应该是['a', 'b', 'c'].任何人都可以帮助阐明为什么会这样吗?未能在文档中找到关于为什么会出现这种情况的提示.

Can't for the life of me figure out why blah[:-0] # [] should be the case, the pattern definitely seems to suggest that it should be ['a', 'b', 'c']. Can anybody help to shed some light on why that is the case? Haven't been able to find mention in the docs as to why that is the case.

推荐答案

-0是0，并且从list包含开头的索引到索引0不包含在内的切片是空的list.

-0 is 0, and a slice that goes from the beginning of a list inclusive to index 0 non-inclusive is an empty list.

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