TheAlgorithms/Python · error · ValueError

Empty string was passed to the function

Error message

Empty string was passed to the function

What it means

Raised by oct_to_decimal(oct_string) in conversions/octal_to_decimal.py:62 when, after str()/strip(), the value is empty. Like its hex sibling, the function first rejects blank input with ValueError('Empty string was passed to the function') before looking at digits or the optional leading '-'.

Source

Thrown at conversions/octal_to_decimal.py:62

    0
    >>> oct_to_decimal("-4055")
    -2093
    >>> oct_to_decimal("2-0Fm")
    Traceback (most recent call last):
        ...
    ValueError: Non-octal value was passed to the function
    >>> oct_to_decimal("")
    Traceback (most recent call last):
        ...
    ValueError: Empty string was passed to the function
    >>> oct_to_decimal("19")
    Traceback (most recent call last):
        ...
    ValueError: Non-octal value was passed to the function
    """
    oct_string = str(oct_string).strip()
    if not oct_string:
        raise ValueError("Empty string was passed to the function")
    is_negative = oct_string[0] == "-"
    if is_negative:
        oct_string = oct_string[1:]
    if not oct_string.isdigit() or not all(0 <= int(char) <= 7 for char in oct_string):
        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__":
    from doctest import testmod

    testmod()

View on GitHub (pinned to f5988cc097)

Solutions

1. Treat blank as missing before calling: if not str(value).strip(): handle the missing case
2. Default to '0' when zero is the sensible interpretation: oct_to_decimal(value.strip() or '0')
3. Use argparse defaults/validation so empty strings never reach the converter

Example fix

# before
oct_to_decimal(args.octal)  # unset optional flag '' -> ValueError

# after
val = args.octal.strip() if args.octal else ''
if not val:
    raise SystemExit('octal value required')
oct_to_decimal(val)

oct_string = str(oct_string).strip()
if not oct_string:
    raise ValueError('octal value is required')

def is_nonempty_str(v: object) -> TypeGuard[str]:
    return isinstance(v, str) and bool(v.strip())

When it happens

Trigger: oct_to_decimal(''), oct_to_decimal(' '), oct_to_decimal(None) (str(None)='None' actually fails the digit check instead — only truly empty/blank strings hit this branch), or empty fields from argparse/file parsing.

Common situations: Optional CLI flags or config keys that default to '' when unset; iterating over split() results that include empty strings; form fields left blank.

Related errors

• Empty string was passed to the function
• Empty string was passed to the function
• No input value was provided
• No value was passed to the function
• Non-hexadecimal value was passed to the function

AI-assisted analysis of TheAlgorithms/Python@f5988cc097 (2026-08-14). Data as JSON: /api/errors/7ca703bcec9cd44c. Report an issue: GitHub.