Python Decimal to Binary converter (without using bin() or output formatting)

Question

There is no input validation for this, but that aside, I would appreciate it if anyone could help me improve the logic of this script.

import math
#Input
num = input("Enter a whole number: ")
#Floors input in case of a non whole number
decimal = math.floor(float(num))
#Variables
exp = 0
divTwo = 1
zeros = 0
total = ""
if decimal < 0:
 total += str('-')
 decimal = -decimal
if decimal == 0:
 total = str('0')
else:
 #Loops while remainder is > 0.
 while int(decimal) > 0:
 #Increases exponent by one if 2^exp is less than or equal to the remainder.
 if 2 ** exp <= int(decimal):
 exp += 1
 else: #Multiplies 2 by the exponent and places zeros in between 1s. Also subtracts from the exponent.
 exp -= 1
 #Determines whether or not to subtract from the remainder and add a '1' to the binary translation or just add a '0' to the binary translation.
 if 2 ** exp <= int(decimal):
 #Counts how many zeros need to be added to the end of the binary translation.
 if 2 ** exp == int(decimal):
 divTwo = int(decimal)
 #Loops until all remaining zeros have been accounted for.
 while divTwo > 1:
 divTwo = divTwo / 2
 zeros += 1
 decimal = int(decimal)
 decimal -= 2 ** exp
 total += str('1')
 else:
 total += str('0')
#Places remaining zeros.
while zeros > 0:
 total += str('0')
 zeros -= 1
#Displays answer.
print ('Binary: ' + total)
input()
#
#
#Or 'bin(decimal)' works too, but this was for fun
#
#

Here is a working version of the script.

• N3buchadnezzar: Just to be sure. You know you can do "{0:b}".format(num) right?
• Confettimaker: I haven't looked into formatting that much.
• N3buchadnezzar: What about bin(x)[2:] then?
• Confettimaker: I did this with the intention of not using bin()

Answer 1

• You can remove half of you code.
  You need the variables exp, total and decimal. The rest are just noise.

• You should remove all the int(decimal)s, decimal is only ever subtracted from, and so it's not going to become a float. And so these are not needed.

1. You can remove all the code in if 2 ** exp == int(decimal):, instead just use exp as you do zeros.

2. You should split your while loop so that it only does one thing at a time. You want an int log and then a while loop that converts the input to binary.

3. You can replace while zeros > 0: with Pythons way to duplicate strings. 0 * zeros.

4. You should make this a function.

This leads to code like:

def binary(number): # 4
 output = ''
 if number < 0:
 output = '-'
 number = -number
 exp = 1
 while 2 ** exp <= number: # 2
 exp += 1
 while number > 0:
 exp -= 1
 if 2 ** exp <= number:
 number -= 2 ** exp
 output += '1'
 else:
 output += '0'
 return output + '0' * exp # 1, 3
number = int(input("Enter a whole number: "))
print('Binary: ' + binary(number))

• Confettimaker: It works for the most part, however it freezes if you input 2. Everything above 2 works. Even 1 works.
• Peilonrayz: @Confettimaker That's correct, I mistakenly at some point removed the = from 2 ** exp <= number.