Hackerrank File I/O and Exception Handling 3

Question 1

What does the `tell()` method return when called on an open file object?

Accepted Answer

The current byte position of the file pointer

Answer

`tell()` returns an integer representing the file pointer's current byte offset from the beginning of the file.

Question 2

Which mode opens a file for exclusive creation, failing if the file already exists?

Accepted Answer

'x'

Answer

Mode `'x'` (exclusive creation) opens the file for writing but raises `FileExistsError` if the file already exists.

Question 3

How do you define a custom exception class named `AppError` in Python?

Accepted Answer

class AppError(Exception):

Answer

User-defined exceptions should subclass `Exception` (not `BaseException`) using standard class inheritance syntax.

Question 4

What happens if an exception raised inside a `with` block is not handled?

Accepted Answer

The context manager's __exit__ is called, then the exception propagates

Answer

`__exit__` is always called (enabling cleanup), and if it returns a falsy value the exception continues to propagate up the call stack.

Question 5

What is the output of `f.read()` called a second time on a file already read to EOF?

Accepted Answer

An empty string ''

Answer

After reaching EOF, `read()` returns an empty string `''` because there are no more bytes to read.

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