Issues with "Exercise 4: Base converter" in Control Flow notebook

[j-piller]

Describe the bugs
A) Final string should be reverted, with e.g. result = result[::-1], to yield the correct result.

python-tutorial/tutorial/tests/test_02_control_flow.py

Lines 412 to 419 in cbd5572

	# Convert to target base
	result = ""
	while decimal > 0:
	digit = decimal % to_base
	result += valid_digits[digit]
	decimal //= to_base
	return f"-{result}" if is_negative else result

        decimal //= to_base

    #TODO: result = result[::-1] to revert the string
    # Test: e.g. -"A00", from_base=16, to_base=13 (2560 in base_10) should return -121C and not -C121)

    return f"-{result}" if is_negative else result

B) In the case of to_base=10 the sign is not added.

python-tutorial/tutorial/tests/test_02_control_flow.py

Lines 409 to 410 in cbd5572

	if to_base == 10:
	return str(decimal)

if to_base == 10: return str(decimal) #TODO: Handle negative numbers e.g. f'-{str(decimal)}' if is_negative else str(decimal)

To Reproduce
Steps to reproduce the behavior:
A. reference_base_converter("-A00", 16, 13)
B. reference_base_converter("-A00", 16, 10) or any negative number converted from base!=10 to base=10

Expected behavior
A: reference_base_converter("-A00", 16, 13) returns -121C [2560 in base 10]
B: reference_base_converter("-A00", 16, 10) returns -2560

Where did you run the tutorial?

• Local installation (conda: jupyter lab)

Additional context
First GitHub reported issue, I apologize for anything unclear.

[edoardob90]

Thanks @j-piller! Good catch of both these bugs.

There's an additional improvement to be made here: checking whether from_base == to_base is done before digits validation, so calling the reference solution like reference_base_converter('G', 10, 10) immediately returns "G", which is clearly wrong (and meaningless) in base 10. We should move digits validation before this check.

python-tutorial/tutorial/tests/test_02_control_flow.py

Lines 382 to 399 in cbd5572

	# Same to and from bases
	if from_base == to_base:
	return number
	# Handle negative numbers
	is_negative = number.strip().startswith("-")
	number = number.strip().removeprefix("-")
	# Remove spaces and convert to uppercase for consistency
	number = number.replace(" ", "").upper()
	# Validate digits
	valid_digits = "0123456789ABCDEF"
	for digit in number:
	if digit not in valid_digits[:from_base]:
	err = f"Invalid digit '{digit}' for base {from_base}"
	raise ValueError(err)