donnemartin/interactive-coding-challenges · error · Exception

Invalid value

Error message

Invalid value

What it means

Bit.update_bit raises a generic Exception('Invalid value') when the value parameter is None or not exactly 0 or 1. Bit fields can only be set to a single bit, so any other value is rejected before set_bit/clear_bit is called.

Source

Thrown at bit_manipulation/bit/bit_solution.ipynb:239

    "        self.number &= mask\n",
    "        return self.number\n",
    "\n",
    "    @validate_index\n",
    "    def clear_bits_msb_to_index(self, index):\n",
    "        mask = (1 << index) - 1\n",
    "        self.number &= mask\n",
    "        return self.number\n",
    "\n",
    "    @validate_index\n",
    "    def clear_bits_index_to_lsb(self, index):\n",
    "        mask = ~((1 << index + 1) - 1)\n",
    "        self.number &= mask\n",
    "        return self.number\n",
    "\n",
    "    @validate_index\n",
    "    def update_bit(self, index, value):\n",
    "        if value is None or value not in (0, 1):\n",
    "            raise Exception('Invalid value')\n",
    "        if self.get_bit(index) == value:\n",
    "            return self.number\n",
    "        if value:\n",
    "            self.set_bit(index)\n",
    "        else:\n",
    "            self.clear_bit(index)\n",
    "        return self.number"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Unit Test"
   ]
  },
  {
   "cell_type": "code",

View on GitHub (pinned to 358f2cc604)

Solutions

1. Convert to int explicitly: update_bit(index, int(bool(value)))
2. Validate/normalize input to 0 or 1 before the call
3. Restructure to use set_bit/clear_bit directly based on a boolean

Example fix

# before
bit.update_bit(index, value)  # value may be 2/None

# after
bit.update_bit(index, 1 if value else 0)

if value not in (0, 1):
    raise ValueError(f'value must be 0 or 1, got {value!r}')
bit.update_bit(index, value)

def is_bit_value(v) -> bool:
    return v in (0, 1)

try:
    bit.update_bit(index, value)
except Exception as e:
    if str(e) == 'Invalid value':
        value = int(bool(value))
        bit.update_bit(index, value)
    else:
        raise

When it happens

Trigger: bit.update_bit(3, 2), bit.update_bit(0, True) (bool is not in (0,1) check? True == 1 so it passes), bit.update_bit(1, None), or passing an int parsed from unvalidated string input like int('5').

Common situations: Passing user-provided or config-driven flag values without normalizing booleans, or mapping textual 'true'/'false' to something other than 0/1.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Invalid index
• Invalid argument: None
• num cannot be None
• num cannot be None
• num cannot be 0 or negative

AI-assisted analysis of donnemartin/interactive-coding-challenges@358f2cc604 (2026-08-28). Data as JSON: /api/errors/c7ae2e9f44b6bc10. Report an issue: GitHub.