Python: object identity question? [duplicate]

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Possible Duplicate:

Python “is” operator behaves unexpectedly with integers

>>>a=123
>>>b=123
>>>a is b
True
>>>id(a)==id(b)
True

My question is, why is id(a) the same as id(b)?.

Aren't they two different instanc开发者_运维技巧es of class int?

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Usually small integers reference the same cached object in memory for efficiency purposes.

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ints are cached. That is an implementation detail that shouldn't matter since ints are immutable anyway.

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variables

a and b 

both are references to the object 123 whose id is unique.

when u assign same value 123 to two diff variables a and b,

then same object 123 is assigned to both variables a and b but reference count made to that object increases in your case refrecnce count for object 123 is two