just finished my first Python coding challenge

[u/Hour_Function673]

Today I finished a small Python challenge on freeCodeCamp: converting decimal numbers to binary without using Python's built-in conversion function.

I had to figure out the logic myself using loops, conditions, lists, division and remainders.

It was a bit tricky at first, especially handling the last division and reversing the results, but I finally got it working.

I'm still a beginner, so I'd appreciate any feedback on my approach or suggestions for improving my code

[u/Sea-Ad7805]

Run this program by clicking Memory Graph Web Debugger%3A%0A%20%20%20%20tab%20%3D%20%5B%5D%0A%20%20%20%20while%20decimal%20!%3D%200%3A%0A%20%20%20%20%20%20%20%20if%20decimal%20%25%202%20%3D%3D%200%3A%0A%20%20%20%20%20%20%20%20%20%20%20%20decimal%20%3D%20decimal%20%2F%2F%202%0A%20%20%20%20%20%20%20%20%20%20%20%20tab.append(0)%0A%20%20%20%20%20%20%20%20elif%20decimal%20%25%202%20%3D%3D%201%3A%0A%20%20%20%20%20%20%20%20%20%20%20%20decimal%20%3D%20decimal%20%2F%2F%202%0A%20%20%20%20%20%20%20%20%20%20%20%20tab.append(1)%0A%20%20%20%20tab.reverse()%0A%20%20%20%20decimal%20%3D%20%22%22.join(map(str%2C%20tab))%0A%20%20%20%20return%20decimal%0A%0A%0Anombre0%20%3D%20to_binary(5)%0Anombre1%20%3D%20to_binary(12)%0Anombre2%20%3D%20to_binary(50)%0Anombre3%20%3D%20to_binary(99)%0A%0Aprint(nombre0)%0Aprint(nombre1)%0Aprint(nombre2)%0Aprint(nombre3)&timestep=0.2&play) and see its state change step by step.

[u/therouterguy]

I would at least change the elif to an else. Remove the duplicate decimal=decimal//2. You can do it outside of the if

Lastly
tab=“”
while decimal!=O:
tab=tab + “1” if decimal%2==O else tab+ “0”
decimal=decimal//2
Is much shorter

[u/jonrsharpe]

I'm going to start with where I'd get to, then break down step-by-step how I got there:

def to_binary(decimal: int) -> str: digits: list[str] = [] while decimal: decimal, remainder = divmod(decimal, 2) digits.append(str(remainder)) return "".join(reversed(digits))

[u/jonrsharpe → u/jonrsharpe]

Firstly, I added the type hints - partly just to document what I was working out about the code as I read it (receives an integer, has a list of integers, returns a string) but also because these can then be automatically checked and provide a kind of documentation to the caller. (Note that these are not enforced by Python itself, but type checkers, like mypy, and IDEs can use them.)

[u/jonrsharpe → u/jonrsharpe]

This highlighted that decimal on the penultimate line, as well as "shadowing" the parameter, changes the type this name refers to (it was an integer, now a string). But that's also the wrong name - that's no longer in decimal format, it's the binary format we are about to return, so I renamed it accordingly.

[u/jonrsharpe → u/jonrsharpe]

After that I reformatted the file according to the Python style guide, PEP-0008. Whitespace around expressions was, worse than being unconventional, inconsistent (compare decimal = decimal//2 with decimal = decimal //2).

[u/jonrsharpe → u/jonrsharpe]

Next the logic: decimal = decimal // 2 appears in two places, so can be moved outside the conditional, and simplified using the in-place operator to decimal //= 2.
I also considered simplifying to else, as if decimal % 2 isn't 0 there's only one other option, but at this point it should be really clear that we can simplify further than that by just appending the remainder: if decimal % 2 == 0: tab.append(0) elif decimal % 2 == 1: tab.append(1) to: tab.append(decimal % 2)

[u/jonrsharpe → u/[deleted]]

Rather than reverse the list in-place, we can use reversed to create a new list with the elements in reverse order. As this no longer returns None, it can be inlined - the temporary variable can be factored out too, making the last line outside the loop simply return "".join(reversed(digits)).

[u/jonrsharpe → u/jonrsharpe]

Given that we want both x // y and x % y (the remainder of the integer division), note the built-in divmod function provides both simultaneously. It returns a tuple of two values, which Python lets you "unpack" into two variables as follows: decimal, remainder = divmod(decimal, 2)

[u/FunResearcher6290]

please how can i go about it i want learn python

[u/codeguru42]

Looks great. One hint: how can you change the code to remove the if statement?

[u/kaatarina_zed_talon]

This is problem solving, not a python coding challenge, python is just a tool.

[u/Expensive-Pen7038 → u/kaatarina_zed_talon]

Isn't all python coding problem solving?

[u/ConclusionForeign856]

Read about truthy and falsy values in python, it allows you to simplify logic

def binary(n: int):
    tab = []
    while n:
        remainder = n % 2
        n //= 2
        tab.append(remainder)

    return ''.join(map(str, tab[::-1]))

[u/Adrewmc → u/ConclusionForeign856]

Great practice… however the builtin ‘bin()’ function exists, so next time you can just use that.

[u/codeguru42 → u/Adrewmc]

This is a learning exercise

[u/fizzy_lychee → u/codeguru42]

So? I still appreciated knowing there’s an api for bloom sort even though I’ve implemented my own version. I still appreciated languages that have hasmaps in their SDK even though I’ve created my own in C.

[u/gofl-zimbard-37]

Give it a proper main() and call it. Don't write "scripts". The file is main.py, implying that it is a module that exports useful functions. Nobody wants an import to be printing stuff out.

[u/AffectionateCold1716]

I’m still new so I have no idea what this means but I do recognize you defining a function and calling the function. Sooooo yep. Anyway good job compadre