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In Python, x is y returns true if the two sides evaluate to the same object; that is, it checks pointer equality. Now I tried something like this: 

>>>a = 2  
>>>a is 2  
True

However.. 

>>>a = 9203409249024  
>>>a is 9203409249024  
False

Why this difference in behavior?

Ankur Ankan
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Nick
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    This is an optimization in Cpython (and perhaps some others) and has been answered here before... I'll look for the dupe... – mgilson Jan 07 '14 at 05:34

1 Answers1

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Python (and other languages) cache small numbers in memory, so that multiple variables that have the value (for example) 2 will point to the same location in memory (and, hence, is returns True).

Hardmath123
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