TheAlgorithms/Python · error · ValueError

Non-binary value was passed to the function

Error message

Non-binary value was passed to the function

What it means

bin_to_hexadecimal raises this ValueError when any character of the input (after an optional leading '-' is removed) is not '0' or '1'. The function then left-pads to a multiple of 4 bits and maps each nibble via a lookup dict, so non-binary characters would cause a KeyError later; validation happens first.

Source

Thrown at conversions/binary_to_hexadecimal.py:49

    >>> bin_to_hexadecimal('a')
    Traceback (most recent call last):
        ...
    ValueError: Non-binary value was passed to the function
    >>> bin_to_hexadecimal('')
    Traceback (most recent call last):
        ...
    ValueError: Empty string was passed to the function
    """
    # Sanitising parameter
    binary_str = str(binary_str).strip()

    # Exceptions
    if not binary_str:
        raise ValueError("Empty string was passed to the function")
    is_negative = binary_str[0] == "-"
    binary_str = binary_str[1:] if is_negative else binary_str
    if not all(char in "01" for char in binary_str):
        raise ValueError("Non-binary value was passed to the function")

    binary_str = (
        "0" * (4 * (divmod(len(binary_str), 4)[0] + 1) - len(binary_str)) + binary_str
    )

    hexadecimal = []
    for x in range(0, len(binary_str), 4):
        hexadecimal.append(BITS_TO_HEX[binary_str[x : x + 4]])
    hexadecimal_str = "0x" + "".join(hexadecimal)

    return "-" + hexadecimal_str if is_negative else hexadecimal_str


if __name__ == "__main__":
    from doctest import testmod

    testmod()

View on GitHub (pinned to f5988cc097)

Solutions

1. Strip '0b' prefix first: bin_to_hexadecimal(bin_str.removeprefix('0b'))
2. Validate with a regex before calling: re.fullmatch(r'-?[01]+', s)
3. If the input is decimal, use a decimal-to-hex path (hex(int(s))) instead

Example fix

# before
bin_to_hexadecimal(bin(255))
# ValueError: Non-binary value was passed to the function

# after
bin_to_hexadecimal(bin(255).removeprefix('0b'))
# '0xff'

import re
s = str(binary_str).strip()
assert re.fullmatch(r'-?[01]+', s), f'not binary: {binary_str!r}'
bin_to_hexadecimal(s)

def is_binary_string(s) -> bool:
    s = str(s).strip().removeprefix('-')
    return s != '' and all(c in '01' for c in s)

try:
    bin_to_hexadecimal(s)
except ValueError as e:
    if 'Non-binary' in str(e):
        raise ValueError('expected binary digits only') from e
    raise

When it happens

Trigger: bin_to_hexadecimal('0x1F') (hex input to a binary function), bin_to_hexadecimal('10 2'), bin_to_hexadecimal(bin(255)) because the '0b' prefix contains 'b', bin_to_hexadecimal('1.01').

Common situations: Wrong-direction conversion (already-hex or decimal strings passed in); passing Python's bin() output without stripping '0b'; locale/typo digit corruption.

Related errors

• Empty string was passed to the function
• Non-binary value was passed to the function
• Empty string was passed to the function
• Non-binary value was passed to the function
• Invalid 'from_type' value: {from_type!r}.\nConversion abbrev

AI-assisted analysis of TheAlgorithms/Python@f5988cc097 (2026-08-14). Data as JSON: /api/errors/91f3f8420862c054. Report an issue: GitHub.