惊喜使用'is'运算符 [英] Surprise using the 'is' operator

问题描述

我认为''是''运算符用于标识相同的对象，

而''==''运算符检查了相等性。好吧，我有一个惊喜

这里：


IDLE 1.1.3

>> a = 10
b = a
a是b

True

>> a == b

True

>> c = 10
a == c

True

>> a是c

True

>>& GT;

我不希望最后一个语句返回True！


我是什么缺少？


谢谢

Tony

解决方案

codefire写道：

我认为''是''运算符用于识别相同的对象，

而''==''操作员检查了相等好吧，我有一个惊喜

这里：


IDLE 1.1.3

>>> a = 10
b = a
a是b

True

>>> a == b

True

>>> c = 10
a == c

True

>>> a是c

True

>>> ;>

我不希望最后一个语句返回True！


我缺少什么？

蟒蛇最严重的死马之一 - 小整数是由翻译缓存的
。也许。因此上述结果。


谷歌就此进行了大量讨论。


Diez

codefireaécrit：

我认为''是''运算符用于识别相同的对象，

而'' '==''运算符检查了相等性。好吧，我有一个惊喜

这里：


IDLE 1.1.3

>>> a = 10
b = a
a是b

True

>>> a == b

True

>>> c = 10
a == c

True

>>> a是c

True


我不希望最后一个语句返回True！

答案是：为什么不呢？整数是否重要？永远不要使用

" is"关于整数，总是==（对于字符串也是如此）

哈哈！


好​​的谢谢你们。


我只是试图检查对象是否相同（对象），没有

知道整数是一个特例。


谢谢，

Tony

I thought the ''is'' operator was used to identify identical objects,
whereas the ''=='' operator checked equality. Well, I got a surprise
here:

IDLE 1.1.3

>>a = 10
b = a
a is b

True

>>a == b

True

>>c = 10
a == c

True

>>a is c

True

>>>

I was NOT expecting the last statement to return True!

What am I missing?

Thanks
Tony

解决方案

codefire wrote:

I thought the ''is'' operator was used to identify identical objects,
whereas the ''=='' operator checked equality. Well, I got a surprise
here:

IDLE 1.1.3

>>>a = 10
b = a
a is b

True

>>>a == b

True

>>>c = 10
a == c

True

>>>a is c

True

>>>>

I was NOT expecting the last statement to return True!

What am I missing?

One of the most severely beaten dead horses of python - small integers are
cached by the interpreter. Maybe. Thus the above results.

Google for a bazillion discussions on this.

Diez

codefire a écrit :

I thought the ''is'' operator was used to identify identical objects,
whereas the ''=='' operator checked equality. Well, I got a surprise
here:

IDLE 1.1.3

>>>a = 10
b = a
a is b

True

>>>a == b

True

>>>c = 10
a == c

True

>>>a is c

True

I was NOT expecting the last statement to return True!

The answer is : Why not? Does it even matter for integers? Never use
"is" on integers, always == ( and on strings too for that matter )

Haha!

OK thanks guys.

I was just trying to check if objects were the same (object), didn''t
know Integers were a special case.

Thanks,
Tony

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