How can I make `bin(30)` return `00011110` instead of `0b11110`? [duplicate]

Using zfill():

Return the numeric string left filled with zeros in a string of length width. A sign prefix is handled correctly. The original string is returned if width is less than len(s).

>>> bin(30)[2:].zfill(8)
'00011110'
>>>

0b is like 0x - it indicates the number is formatted in binary (0x indicates the number is in hex).

See How do you express binary literals in python?

See http://docs.python.org/dev/whatsnew/2.6.html#pep-3127-integer-literal-support-and-syntax

To strip off the 0b it's easiest to use string slicing: bin(30)[2:]

And similarly for format to 8 characters wide:

('00000000'+bin(30)[2:])[-8:]

Alternatively you can use the string formatter (in 2.6+) to do it all in one step:

"{0:08b}".format(30)

Take advantage of the famous format() function with the lesser known second argument and chain it with zfill()

'b' - Binary 'x' - Hex 'o' - Octal 'd' - Decimal

>>> print format(30, 'b')
11110
>>> print format(30, 'b').zfill(8)
00011110

Should do. Here 'b' stands for binary just like 'x', 'o' & 'd' for hexadecimal, octal and decimal respectively.

You can use format in Python 2 or Python 3:

>> print( format(15, '08b') )
00001111

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