之间＆QUOT区别;如果x＆QUOT;和＆QUOT;如果x不是无＆QUOT; [英] Difference between "if x" and "if x is not None"

问题描述

看来，如果x是几乎像短手长如果x不是无语法。他们是功能相同，还是有情况下，为第X两个将评估不同的给定值？

It appears that "if x" is almost like short-hand for the longer "if x is not None" syntax. Are they functionally identical or are there cases where for a given value of x the two would evaluate differently?

我将承担行为，也应该是不同的Python实现相同的 - 但如果有细微的差别将是巨大知道

I would assume the behavior should also be identical across Python implementations - but if there are subtle differences it would be great to know.

推荐答案

在下列情况下：

test = False 
test = "" 
test = 0
test = 0.0 
test = []
test = () 
test = {} 
test = set()

在如果测试将有所不同：

if test: #False

if test is not None: #True 

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