PCAP Exceptions and File I/O Practice Question
Which TWO of the following are built-in Python exceptions?
⚠ Common exam trap
Python Institute often tests the distinction between built-in exceptions and user-defined or non-existent exceptions, and the trap here is that candidates may confuse InputError or FileReadError with real built-in exceptions like EOFError or OSError, or assume that any error related to input or files must be a built-in exception.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
ValueError
ValueError (C) is a built-in Python exception that is raised when a built-in operation or function receives an argument with the correct type but an inappropriate value, such as int('abc'). FileNotFoundError (D) is a built-in exception in Python 3, raised when a file or directory is requested but does not exist, commonly encountered during file I/O operations like open().
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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CustomException
Why it's wrong here
CustomException is not a built-in Python exception; it represents a placeholder for user-defined exception classes. Developers typically create such classes by subclassing the built-in `Exception` base class (or a subclass like `RuntimeError`) to handle application-specific error conditions. The Python standard library does not include any class named `CustomException`, so seeing it in code signals a custom, project-specific definition.
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InputError
Why it's wrong here
InputError is not a built-in exception in Python's standard library. The built-in `ValueError` is the closest match, raised when a function receives an argument of the correct type but an inappropriate value, while `TypeError` handles type mismatches. Although some third-party libraries or frameworks define an `InputError` class, the Python language itself does not provide one, so referring to it as a built-in exception is incorrect.
- ✓
ValueError
Why this is correct
ValueError is a built-in exception in Python, defined in the `builtins` module and raised when a function receives an argument of the correct type but an invalid value—for example, `int('abc')` or `math.sqrt(-1)`. It is deliberately distinct from `TypeError`, which covers type mismatches, allowing programmers to catch value-specific errors cleanly. As a built-in, it is always available without any import and is part of the core exception hierarchy.
- ✓
FileNotFoundError
Why this is correct
FileNotFoundError is a built-in exception in Python, introduced in version 3.3 as a subclass of `OSError` and raised when a file or directory is requested but does not exist on the filesystem. It carries an `errno` attribute (typically `ENOENT`) and a `filename` attribute, making it useful for precise error handling in I/O operations. Because it inherits from `OSError`, a bare `except OSError` will also catch it, but catching the specific subclass allows more targeted recovery.
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FileReadError
Why it's wrong here
FileReadError is not a built-in exception in Python; the standard library includes `OSError`, `IOError` (an alias of `OSError`), and more specific subclasses like `FileNotFoundError` and `PermissionError`, but no `FileReadError`. This name might appear in custom code, third-party libraries, or other programming languages, but it is not defined in Python's `builtins` or `exceptions` modules. Using it without a custom definition raises a `NameError`, so it cannot be considered a built-in exception.
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