Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.


A fun challenge for anybody (not only Python developers): Binary to Digits!

:point_right: ALERT :point_left:

This isn't a question, it's a little challenge for anybody to try.

I thought of a challenge this morning to convert binary to digits.

I have thought of converting digits to binary, but binary to digits seems easier.

If you don't know how to convert binary to numbers you can check out this video.

You actually can code this is any language, but Python is the preferred over here.

If anyone wants to try, please try to solve the problem on your own and once you've solved it, you may post your code below (optional).

I am going to post my own code in a couple programming languages including Python.

I hope you enjoy the challenge :)



No peeking until you complete the challenge :)

Also, if you want more challenges like this occasionally, please post below :)

5 Answers

My answer in Python:

def binary_to_digit(binary_str):
    result = 0
    for idx, num in enumerate(binary_str[::-1]):
        if num == '1':
            result += 2 ** idx
        elif num == '0':
            # This line of code is just for raising an error if the string has anything but 1s and 0s
            raise ValueError("Only 1s and 0s are allowed in binary")
    return result


Steven Parker
Steven Parker
216,083 Points

Did you forget to return the result?

Oops sorry XP

I edited my answer.

I didn't copy-and-paste my code i just wrote my code in my local machine (I used IDLE) and I just tried to memorize it instead of copy-and-pasting.

Steven Parker
Steven Parker
216,083 Points

:question: Is it kosher to "Best Answer" yourself? :laughing:

My answer in Ruby:

def binary_to_digit(binary_str)
    result = 0
    idx = 0
    bits_reverse = binary_str.reverse.split('')
    bits_reverse.each do |bit|
        result += 2 ** idx if bit == '1'
        idx += 1
    return result
Steven Parker
Steven Parker
216,083 Points

In Javascript:

function binary_to_digit(binary_str)
  let result = parseInt(binary_str, 2);
  if (isNaN(result))
    console.log("Only 1s and 0s are allowed in binary");
  return result;

Hmm, I didn't know you can pass in a second parameter to JavaScript's parseInt. That's interesting! :)

Steven Parker
Steven Parker
216,083 Points

Yes, parameter 2 (optional) is radix, I used 2 (binary) here. Very handy in this case!

Are you able to solve this task without using the parseInt function at all? Just an additional challenge :)

parseInt is only going to return NaN if the first character can't be converted.

So you'll get the log statement with "20" but "13" will pass through and you'll get a return value of 1.

Steven Parker
Steven Parker
216,083 Points

Sure, you can do it without parseInt, just like you can check every digit for legality.

But I'm not sure I'd call either a "challenge" any more than I would apply that word to digging a 9-foot deep hole compared to digging a 2-foot deep one. :laughing:

But if you like programming challenges, have you seen Code Wars?

Dave Laffan
Dave Laffan
4,604 Points

Ok, I got this. The only thing I can say with confidence is I know there will be a million better and more efficient ways of doing it, but I'm happy with that because I'm new to all this and I did it based only on what I've learned so far :smile:

def binary_to_digits(arg1):
    binary_list = list(arg1)
    count = 1
    decimal = 0
    for each_entry in reversed(binary_list):
        if each_entry == '1':
            decimal = decimal + count
        count += count

Good job! No, I can't think of a way to do this a million times better. There might be simpler ways, but this is probably the cleanest way to do it out of all of the ways I can think of :)


Dave Laffan
Dave Laffan
4,604 Points

Oh, cool, thanks!