How to get binary representation of negative numbers in python [duplicate]

Question

When I enter bin(-3) it just shows -0b11.

Which is not what I want. It just keeps that - sign and convert the number. I want the actual representation of negative numbers.

Is there any method in python which does that?

@jonrsharpe Yeah two complement representation. Upto, standard 32 bit. — Bhavesh Munot
– Bhavesh Munot, Commented Feb 7, 2015 at 15:01

falsetru · Accepted Answer · 2015-02-07 15:13:26Z

26

Depending on how many binary digit you want, subtract from a number (2ⁿ):

>>> bin((1 << 8) - 1)
'0b11111111'
>>> bin((1 << 16) - 1)
'0b1111111111111111'
>>> bin((1 << 32) - 1)
'0b11111111111111111111111111111111'

UPDATE

Using following expression, you can cover both positive and negative case:

>>> bin(((1 << 32) - 1) & -5)
'0b11111111111111111111111111111011'

answered Feb 7, 2015 at 15:01

falsetru

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3 Comments

And even >>> bin((1 << 64) - 1) '0b1111111111111111111111111111111111111111111111111111111111111111'

For bonus points, you can cover positive and negative in one go with bitwise and: bin(((1 << 32) - 1) & -5)

@cobbal, Thank you for your comment. I updated the answer according to you.