Converting integer to binary in python

Question

In order to convert an integer to a binary, I have used this code :

>>> bin(6)  
'0b110'

and when to erase the '0b', I use this :

>>> bin(6)[2:]  
'110'

What can I do if I want to show 6 as 00000110 instead of 110?

Answer 1

>>> '{0:08b}'.format(6)
'00000110'

Just to explain the parts of the formatting string:

• {} places a variable into a string
• 0 takes the variable at argument position 0
• : adds formatting options for this variable (otherwise it would represent decimal 6)
• 08 formats the number to eight digits zero-padded on the left
• b converts the number to its binary representation

If you're using a version of Python 3.6 or above, you can also use f-strings:

>>> f'{6:08b}'
'00000110'

Answer 2

Just another idea:

>>> bin(6)[2:].zfill(8)
'00000110'

Shorter way via string interpolation (Python 3.6+):

>>> f'{6:08b}'
'00000110'

Answer 3

A bit twiddling method...

>>> bin8 = lambda x : ''.join(reversed( [str((x >> i) & 1) for i in range(8)] ) )
>>> bin8(6)
'00000110'
>>> bin8(-3)
'11111101'

Answer 4

Just use the format function

format(6, "08b")

The general form is

format(<the_integer>, "<0><width_of_string><format_specifier>")

Answer 5

eumiro's answer is better, however I'm just posting this for variety:

>>> "%08d" % int(bin(6)[2:])
00000110

Answer 6

numpy.binary_repr(num, width=None) has a magic width argument

Relevant examples from the documentation linked above:

>>> np.binary_repr(3, width=4)
'0011'

The two’s complement is returned when the input number is negative and width is specified:

>>> np.binary_repr(-3, width=5)
'11101'

Answer 7

.. or if you're not sure it should always be 8 digits, you can pass it as a parameter:

>>> '%0*d' % (8, int(bin(6)[2:]))
'00000110'

Answer 8

Going Old School always works

def intoBinary(number):
binarynumber=""
if (number!=0):
    while (number>=1):
        if (number %2==0):
            binarynumber=binarynumber+"0"
            number=number/2
        else:
            binarynumber=binarynumber+"1"
            number=(number-1)/2

else:
    binarynumber="0"

return "".join(reversed(binarynumber))

Answer 9

('0' * 7 + bin(6)[2:])[-8:]

or

right_side = bin(6)[2:]
'0' * ( 8 - len( right_side )) + right_side

Answer 10

Assuming you want to parse the number of digits used to represent from a variable which is not always constant, a good way will be to use numpy.binary.

could be useful when you apply binary to power sets

import numpy as np
np.binary_repr(6, width=8)

Answer 11

even an easier way

my_num = 6
print(f'{my_num:b}')

Answer 12

The best way is to specify the format.

format(a, 'b')

returns the binary value of a in string format.

To convert a binary string back to integer, use int() function.

int('110', 2)

returns integer value of binary string.

Answer 13

def int_to_bin(num, fill):
    bin_result = ''

    def int_to_binary(number):
        nonlocal bin_result
        if number > 1:
            int_to_binary(number // 2)
        bin_result = bin_result + str(number % 2)

    int_to_binary(num)
    return bin_result.zfill(fill)

Answer 14

You can use just:

"{0:b}".format(n)

In my opinion this is the easiest way!