PCAP Cheat Sheet 2026

The 30 highest-yield PCAP facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What does the `'b'` flag in `open('file', 'rb')` indicate? → Binary mode
2. What is the correct syntax to create a tuple in Python? → tuple = (1, 2, 3)
3. Which data structure is used to store a sequence of items that are ordered and changeable in Python? → List
4. Which of the following is used to define a function in Python? → def
5. What is the `nonlocal` keyword used for inside a nested function? → To modify a variable defined in the nearest enclosing non-global scope
6. Which exception is raised when you try to open a file that does not exist? → FileNotFoundError
7. Which built-in function returns the number of items in a container? → len()
8. What does `os.path.join('folder', 'file.txt')` return on Linux? → folder/file.txt
9. How do you create a list in Python? → list = [1, 2, 3]
10. What does `abs(-5)` return? → 5
11. What happens if an exception is raised inside a `finally` block? → It replaces any previously raised exception
12. Which of the following is a valid variable name in Python? → variable_ name
13. How do you check if a key exists in a dictionary? → if key in dict:
14. What does `except Exception as e:` allow you to do? → Access the exception object via the variable `e`
15. What does the `@classmethod` decorator do? → Passes the class as the first argument instead of the instance
16. How do you define a class variable (shared by all instances) in Python? → Declare it outside any method, inside the class body
17. What does `file.readlines()` return? → A list of strings, one per line
18. What does the `__name__ == '__main__'` guard do? → Prevents code from running when the module is imported
19. Which dunder method allows an object to be represented as a string when printed? → __str__
20. What does `sorted()` return? → A new sorted list
21. What does the `enumerate()` function return when iterating? → A tuple of (index, value)
22. Which module provides `namedtuple` for creating tuple subclasses with named fields? → collections
23. Which function from the `os` module returns the current working directory? → os.getcwd()
24. What is a closure in Python? → A function that captures variables from its enclosing scope
25. What is the base class for all built-in exceptions in Python? → BaseException
26. Which exception is raised when accessing an index that does not exist in a list? → IndexError
27. What does `functools.wraps` do when used in a decorator? → Preserves the original function's metadata
28. What does the `copy` module's `deepcopy()` function do? → Recursively copies an object and all objects it references
29. How do you raise a custom exception in Python? → raise Exception('msg')
30. What happens if no exception is raised in a `try` block that has an `else` clause? → The else block is executed