base-A to base-B converter

convert_base.py

import os


DEBUG = os.environ.get("DEBUG_CONVERTER") or False
DIGITS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"


# in order to convert a number from base-A to base-B
# we have to convert base-A to base-10 then convert the output to base-B
# works if A and B is greater than 1 and less than len(DIGITS)
def main():
    base_from = abs(int(input("Enter base from: ")))
    base_to = abs(int(input("Enter base to: ")))
    value = input("Enter value: ")

    base_10_value = base_n_to_base_10(base_from, value)
    base_to_value = base_10_to_base_n(base_to, base_10_value)

    print()
    print(base_10_value)
    print(base_to_value)


def base_n_to_base_10(base, value):
    if DEBUG:
        print(f"BASE {base} TO BASE 10")

    values = str(value).split(".")
    int_part = values[0]

    output = 0.0

    # compute the integer part
    for ch in int_part:
        prev_value = output
        output *= base
        output += int(ch, base)

        if DEBUG:
            print(f"({prev_value} * {base}) + {ch} = {output}")

    if DEBUG:
        print()

    # if the value has decimal part
    if len(values) > 1:
        frac_part = values[1]

        # compute the decimal part
        # for each (index, character) in enumerated frac_part
        # btw, enumerate([a, b, c]) is just [(0, a), (1, b), (2, c)]
        for i, ch in enumerate(frac_part):
            prev_value = output
            output += int(ch, base) * base**(-i - 1)
            if DEBUG:
                print(f"{prev_value} + {ch} * {base}^({-i - 1}) -> {output}")

    if DEBUG:
        print()

    return str(output)


def base_10_to_base_n(base, value):
    if DEBUG:
        print(f"BASE 10 TO BASE {base}")

    # divide the value into two parts
    output = ""
    int_value = int(float(value))
    frac_value = float(value) - float(int_value)

    # compute the integer part
    while int_value > 0:
        copy = int_value
        remainder = int_value % base
        output = DIGITS[remainder] + output
        int_value //= base

        if DEBUG:
            print(f"{copy} % {base} = {remainder} -> {output}")

    # if the value has decimal part
    if frac_value:
        output += "."

        # compute the compute the decimal part
        for _ in range(10):
            copy = frac_value
            frac_value *= base
            digit = int(frac_value)
            output += DIGITS[digit]
            frac_value -= digit

            if DEBUG:
                print(f"{copy} * {base} = {digit} -> {output}")

    if DEBUG:
        print()

    return output


if __name__ == "__main__":
    main()