Solution: Decimal to Binary

Write a function that returns the binary value (as string) for a positive integer decimal number

Function definition

def dec_to_binary(n):
    binary = ""
    while n != 0:
        binary = str(n % 2) + binary
        n = n // 2
    return binary

Using a recursive function:

def dec_to_binary(n):
    if n==0: return '' # condition to stop the recursive process
    else:
        return dec_to_binary(n // 2) + str(n % 2) # recursive function call

Testing

Check if your function returns the expected value using the cell below.

import unittest

class UnitTests(unittest.TestCase):
    def test_type(self):
        self.assertEqual(type(dec_to_binary(10)), type('1010'), 'The function should return a string')
    def test_size(self):
        self.assertEqual(len(dec_to_binary(100)), 7, 'The function should return a string with lenght=7')
    def test_result_odd(self):
        self.assertEqual(dec_to_binary(101), '1100101', 'The binarie for 200 should be 1100101')
    def test_result_even(self):
        self.assertEqual(dec_to_binary(200), '11001000', 'The binarie for 200 should be 11001000')

unittest.main(argv=[''], verbosity=2,exit=False)

test_result_even (__main__.UnitTests) ... 

ok
test_result_odd (__main__.UnitTests) ... 

ok
test_size (__main__.UnitTests) ... 

ok
test_type (__main__.UnitTests) ... 

ok

----------------------------------------------------------------------
Ran 4 tests in 0.003s

OK

<unittest.main.TestProgram at 0x7fe148afae10>