How do you express binary literals in Python

Question

How do you express an integer as a binary number with Python literals   I was easily able to find the answer for hex    gt  gt  gt  0x12AF 4783  gt  gt  gt  0x100 256   and octal    gt  gt  gt  01267 695  gt  gt  gt  0100 64   How do you use literals to express binary in Python     Summary of Answers   Python 2 5 and earlier  can express binary using int  01010101111  2  but not with a literal  Python 2 5 and earlier  there is no way to express binary literals  Python 2 6 beta  You can do like so  0b1100111 or 0B1100111  Python 2 6 beta  will also allow 0o27 or 0O27  second character is the letter O  to represent an octal  Python 3 0 beta  Same as 2 6  but will no longer allow the older 027 syntax for octals

User · Answer

How do you express binary literals in Python?

They're not "binary" literals, but rather, "integer literals". You can express integer literals with a binary format with a 0 followed by a B or b followed by a series of zeros and ones, for example:

>>> 0b0010101010
170
>>> 0B010101
21

From the Python 3 docs, these are the ways of providing integer literals in Python:

Integer literals are described by the following lexical definitions:
integer      ::=  decinteger | bininteger | octinteger | hexinteger
decinteger   ::=  nonzerodigit (["_"] digit)* | "0"+ (["_"] "0")*
bininteger   ::=  "0" ("b" | "B") (["_"] bindigit)+
octinteger   ::=  "0" ("o" | "O") (["_"] octdigit)+
hexinteger   ::=  "0" ("x" | "X") (["_"] hexdigit)+
nonzerodigit ::=  "1"..."9"
digit        ::=  "0"..."9"
bindigit     ::=  "0" | "1"
octdigit     ::=  "0"..."7"
hexdigit     ::=  digit | "a"..."f" | "A"..."F"
There is no limit for the length of integer literals apart from what can be stored in available memory.

Note that leading zeros in a non-zero decimal number are not allowed. This is for disambiguation with C-style octal literals, which Python used before version 3.0.

Some examples of integer literals:
7     2147483647                        0o177    0b100110111
3     79228162514264337593543950336     0o377    0xdeadbeef
      100_000_000_000                   0b_1110_0101
Changed in version 3.6: Underscores are now allowed for grouping purposes in literals.

Other ways of expressing binary:

You can have the zeros and ones in a string object which can be manipulated (although you should probably just do bitwise operations on the integer in most cases) - just pass int the string of zeros and ones and the base you are converting from (2):

>>> int('010101', 2)
21

You can optionally have the 0b or 0B prefix:

>>> int('0b0010101010', 2)
170

If you pass it 0 as the base, it will assume base 10 if the string doesn't specify with a prefix:

>>> int('10101', 0)
10101
>>> int('0b10101', 0)
21

Converting from int back to human readable binary:

You can pass an integer to bin to see the string representation of a binary literal:

>>> bin(21)
'0b10101'

And you can combine bin and int to go back and forth:

>>> bin(int('010101', 2))
'0b10101'

You can use a format specification as well, if you want to have minimum width with preceding zeros:

>>> format(int('010101', 2), '{fill}{width}b'.format(width=10, fill=0))
'0000010101'
>>> format(int('010101', 2), '010b')
'0000010101'

User · Answer

I ve tried this in Python 3 6 9 Convert Binary to Decimal  gt  gt  gt  0b101111 47   gt  gt  gt  int  101111  2  47  Convert Decimal to binary  gt  gt  gt  bin 47   0b101111   Place a 0 as the second parameter python assumes it as decimal   gt  gt  gt  int  101111  0  101111

User · Answer

For reference mdash future Python possibilities  Starting with Python 2 6 you can express binary literals using the prefix 0b or 0B    gt  gt  gt  0b101111 47   You can also use the new bin function to get the binary representation of a number    gt  gt  gt  bin 173   0b10101101    Development version of the documentation  What s New in Python 2 6

User · Answer

As far as I can tell Python  up through 2 5  only supports hexadecimal  amp  octal literals   I did find some discussions about adding binary to future versions but nothing definite

User · Answer

0 in the start here specifies that the base is 8  not 10   which is pretty easy to see     gt  gt  gt  int  010101   0  4161   If you don t start with a 0  then python assumes the number is base 10    gt  gt  gt  int  10101   0  10101

User · Answer

gt  gt  gt  print int  01010101111  2  687  gt  gt  gt  print int  11111111  2  255   Another way

User · Answer

I am pretty sure this is one of the things due to change in Python 3 0 with perhaps bin   to go with hex   and oct     EDIT  lbrandy s answer is correct in all cases

User · Answer

Another good method to get an integer representation from binary is to use eval   Like so  def getInt binNum   0       return eval eval  0b    str n     I guess this is a way to do it too  I hope this is a satisfactory answer  D

[python] How do you express binary literals in Python?

How do you express binary literals in Python?

Other ways of expressing binary:

Converting from int back to human readable binary:

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