为什么1 +++ 2 = 3?

问题描述

Python如何计算表达式1+++2?

How does Python evaluate the expression 1+++2?

我插入了多少个+，它正在打印3作为答案.任何人都可以解释这种行为

How many ever + I put in between, it is printing 3 as the answer. Please can anyone explain this behavior

对于1--2，它正在打印3，对于1---2，它正在打印-1

And for 1--2 it is printing 3 and for 1---2 it is printing -1

推荐答案

您的表达式与以下内容相同:

Your expression is the same as:

1+(+(+2))

任何数字表达式都可以在-之前使其为负，或者在+之后不执行任何操作(存在对称性选项).带有负号:

Any numeric expression can be preceded by - to make it negative, or + to do nothing (the option is present for symmetry). With negative signs:

1-(-(2)) = 1-(-2)
         = 1+2
         = 3

和

1-(-(-2)) = 1-(2)
          = -1

我看到您澄清了您的问题，说您来自C背景.在Python中，C中没有像++和--这样的增量运算符，这可能是造成混淆的原因.要在Python中递增或递减变量i或j，请使用以下样式:

I see you clarified your question to say that you come from a C background. In Python, there are no increment operators like ++ and -- in C, which was probably the source of your confusion. To increment or decrement a variable i or j in Python use this style:

i += 1
j -= 1

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