Functions and Data Structures

Answers and Descriptions:

1. Answer: Built-in functions (e.g., print()) are predefined in Python; user-defined functions are created by the programmer.
   Description: Built-in functions are ready-to-use, while user-defined functions (e.g., def my_func():) allow custom logic tailored to specific needs.

2. Answer: Variable scope determines where a variable is accessible; local variables are within a function, global variables are outside.
   Description: A local variable in a function isn’t accessible outside it, while a global variable can be accessed anywhere unless shadowed.

3. Answer:

   def factorial(n):
       if n == 0:
           return 1
       return n * factorial(n - 1)
   num = int(input("Enter a number: "))
   print("Factorial is:", factorial(num))

   Description: The recursive function calculates factorial (e.g., 5! = 5 * 4 * 3 * 2 * 1). It returns 1 for 0 and multiplies n by factorial(n-1) otherwise.

4. Answer: Lists are mutable (can be changed); tuples are immutable (cannot be changed).
   Description: Lists (e.g., [1, 2, 3]) allow modifications like append(), while tuples (e.g., (1, 2, 3)) are fixed, useful for constant data.

5. Answer:

   my_dict = {"name": "Alice", "age": 17, "grade": 13}
   print("Keys:", my_dict.keys())
   print("Values:", my_dict.values())

   Description: The dictionary stores key-value pairs. The keys() method returns keys (e.g., name, age), and values() returns values (e.g., Alice, 17).