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Modified octal_to_decimal #3243

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30 changes: 22 additions & 8 deletions conversions/octal_to_decimal → conversions/octal_to_decimal.py
Original file line number Diff line number Diff line change
Expand Up @@ -9,26 +9,40 @@ def oct_to_decimal(oct_string: str) -> int:
>>> oct_to_decimal("-45")
-37
>>> oct_to_decimal("2-0Fm")
Traceback (most recent call last):
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These are optional and do not add much value

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I added them because the doctest failed without them.

...
ValueError: Non-octal value was passed to the function
>>> oct_to_decimal("")
Traceback (most recent call last):
...
ValueError: Empty string value was passed to the function
>>> oct_to_decimal("19")
Traceback (most recent call last):
...
ValueError: Non-octal value was passed to the function
"""
# Strip oct_string of whitespaces
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This comment repeats what the code says. Comments should not be about what the code is doing, but should be about why we are doing something. Why are we removing whitespace? Why are we removing the minus sign.

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Ok

oct_string = str(oct_string).strip()
if not oct_string:
raise ValueError("Empty string was passed to the function")
raise ValueError("Empty string value was passed to the function")

# Check if oct_string is a negative value
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This comment repeats what the code says.

is_negative = oct_string[0] == "-"
if is_negative:
# Remove (-) from oct_string
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This comment repeats what the code says.

oct_string = oct_string[1:]
if not all(0 <= int(char) <= 7 for char in oct_string):

# check if oct_string is an octal value and convert
if oct_string.isdecimal() and all(0 <= int(char) <= 7 for char in oct_string):
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These are redundant tests. The first one cannon pass if the second one does not pass. The original formulation is more consise.

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Thanks for reviewing. In the original, int(char) in the iterable passed to the all() function returns error that is not handled by the ValueError raised when char is not an integer value. It's why I modified it so.

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@cclauss cclauss Oct 13, 2020

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A ValueError is still raised. This is why I encourage doctests. It is not necessary that we raise all exceptions ourselves. It is only important that an appropriate exception is raised when garbage data is received.

>>> int('a')
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ValueError: invalid literal for int() with base 10: 'a'

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Ok

decimal_number = 0
for char in oct_string:
decimal_number = 8 * decimal_number + int(char)
if is_negative:
decimal_number = -decimal_number
return decimal_number
else:
# else raise exception
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This comment repeats what the code says.

raise ValueError("Non-octal value was passed to the function")
decimal_number = 0
for char in oct_string:
decimal_number = 8 * decimal_number + int(char)
if is_negative:
decimal_number = -decimal_number
return decimal_number


if __name__ == "__main__":
Expand Down