Python int to binary string?

Question

Are there any canned Python methods to convert an Integer (or Long) into a binary string in Python?

There are a myriad of dec2bin() functions out on Google... But I

Answer 1

If you're looking for bin() as an equivalent to hex(), it was added in python 2.6.

Example:

>>> bin(10)
'0b1010'

Answer 2

This is for python 3 and it keeps the leading zeros !

print(format(0, '08b'))

Answer 3

Here is the code I've just implemented. This is not a method but you can use it as a ready-to-use function!

def inttobinary(number):
  if number == 0:
    return str(0)
  result =""
  while (number != 0):
      remainder = number%2
      number = number/2
      result += str(remainder)
  return result[::-1] # to invert the string

Answer 4

As the preceding answers mostly used format(), here is an f-string implementation.

integer = 7
bit_count = 5
print(f'{integer:0{bit_count}b}')

Output:

00111

For convenience here is the python docs link for formatted string literals: https://docs.python.org/3/reference/lexical_analysis.html#f-strings.

Answer 5

Here's yet another way using regular math, no loops, only recursion. (Trivial case 0 returns nothing).

def toBin(num):
  if num == 0:
    return ""
  return toBin(num//2) + str(num%2)

print ([(toBin(i)) for i in range(10)])

['', '1', '10', '11', '100', '101', '110', '111', '1000', '1001']

Answer 6

Yet another solution with another algorithm, by using bitwise operators.

def int2bin(val):
    res=''
    while val>0:
        res += str(val&1)
        val=val>>1     # val=val/2 
    return res[::-1]   # reverse the string

A faster version without reversing the string.

def int2bin(val):
   res=''
   while val>0:
       res = chr((val&1) + 0x30) + res
       val=val>>1    
   return res