[issue25999] Add support of native number in bin()

[SonokoMizuki]

New submission from SonokoMizuki:

Add support of negative number in bin().
Currently, bin(-5) returns '-0b101', It is not intuitive.
I think bin() should return two's complement.

I suggest new bin().
New second argument is bit size.
if first argument is negative number and bit size is given, bin() will return 
two's complement.

example)
>>> bin(12)
'0b1100'
>>> bin(-12)
'-0b1100'
>>> bin(-12,8)
'0b0100'
>>> bin(-12,3) # if not enough bit size, bin will return value as usual.
'-0b100'

--
components: Argument Clinic
messages: 257408
nosy: larry, mizuki
priority: normal
severity: normal
status: open
title: Add support of native number in bin()
type: behavior
versions: Python 2.7, Python 3.2, Python 3.3, Python 3.4, Python 3.5, Python 3.6

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[issue25999] Add support of native number in bin()

[SonokoMizuki]

SonokoMizuki added the comment:

It is nice solution. I can get negative number all right. thanks
but, I feel bad that bin(-5) returns '-0b101'
sorry

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[issue25999] Add support of native number in bin()

[SonokoMizuki]

SonokoMizuki added the comment:

That's right. currently python can not  distinguish positive number or negative 
number.

>>> a = bin(-5,10)
>>> int(a,2)
1019

I think reason of  ambiguity is decode function( int() ). 
So, I suggest new decode function.
(example) 
>>> b2i('0b1011',negative=True)
-5
>>> b2i('0b1011',negative=False)
11

( I do not know whether it is good to add special function for binary..., sorry)

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[issue25999] Add support of native number in bin()

[SonokoMizuki]

SonokoMizuki added the comment:

I see.
I grasp to write own function is best.
thanks (^-^)

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[issue25999] Add support of negative number in bin()

[SonokoMizuki]

Changes by SonokoMizuki :


--
title: Add support of native number in bin() -> Add support of negative number 
in bin()

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