CODEWITHSUNDEEP
pythonbit-manipulation
Complex
Complex

Reputation: 1

how to understand i & -i in python? bit manipulation in python

I find '&' in python means 'and' operation based on bit expression. Recently, I find a very smart code and one line is like 'i & -i' where i is a integer. How to understand the result of 'i & -i'. In addition, how python deal with negative integer '-i' for bit manipulation?

Upvotes: 0

Views: 388

Answers (1)

olegarch
olegarch

Reputation: 3891

"i & -i" - this is clear all bits "1", but last significant one. For example:

i = 10(dec) = 00001010(bin)

i & -i will be 00000010(bin) = 2(dec)

By math terms, "i & -i" returns maximal 2^N, which is divider of "i".

More examples:

i(dec)   i(bin)     i&-i
 1            1        1
 5          101        1
 8         1000     1000
12         1100     0100

Upvotes: 1

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