PCEP-30-02 4.1 working with functio.txt

PCEP-30-02 4.1 working with functions in Python, including defining and invoking user-defined functions, using the return keyword, understanding the None keyword, and working with recursion:

1. What is the correct way to define a function in Python?
   A) function my_function():
   B) def my_function():
   C) define my_function():
   D) func my_function():

2. What is the output of the following code?
   ```python
   def greet(name):
       print(f"Hello, {name}!")
   
   greet("Alice")
   ```
   A) Hello, Alice!
   B) Alice
   C) Nothing (no output)
   D) Error

3. Which keyword is used to return a value from a function?
   A) give
   B) return
   C) yield
   D) send

4. What is the output of this code?
   ```python
   def add(a, b):
       return a + b
   
   result = add(3, 4)
   print(result)
   ```
   A) 3
   B) 4
   C) 7
   D) None

5. What is a generator function in Python?
   A) A function that generates random numbers
   B) A function that uses the 'yield' keyword to return values
   C) A function that creates other functions
   D) A function that only returns None

6. What is the purpose of the 'None' keyword in Python?
   A) To represent a null or empty value
   B) To stop a function execution
   C) To define a variable without initializing it
   D) To create an empty list

7. What is recursion in programming?
   A) A loop that runs infinitely
   B) A function that calls itself
   C) A method to sort data
   D) A way to define multiple functions at once

8. What is the output of this recursive function?
   ```python
   def countdown(n):
       if n <= 0:
           return
       print(n)
       countdown(n-1)
   
   countdown(3)
   ```
   A) 3 2 1
   B) 1 2 3
   C) 3 3 3
   D) Error (infinite recursion)

9. Which of the following is true about Python functions?
   A) They must always return a value
   B) They can have multiple return statements
   C) They can only have one parameter
   D) They must be defined before the main program

10. What happens if a function doesn't have a return statement?
    A) It returns 0
    B) It returns None
    C) It raises an error
    D) It returns an empty string

11. How do you call a function named 'my_function' with no arguments?
    A) call my_function
    B) my_function
    C) my_function()
    D) run my_function

12. What is the output of this code?
    ```python
    def multiply(a, b=2):
        return a * b
    
    print(multiply(3))
    ```
    A) 3
    B) 2
    C) 6
    D) Error

13. What is a benefit of using functions in programming?
    A) They make the code run faster
    B) They reduce code duplication
    C) They increase memory usage
    D) They always improve algorithm efficiency

14. What is the difference between a function and a generator?
    A) Functions use 'return', generators use 'yield'
    B) Functions can have parameters, generators cannot
    C) Generators are faster than functions
    D) Functions can be recursive, generators cannot

15. What is the output of this code?
    ```python
    def greet():
        return "Hello"
        print("World")
    
    print(greet())
    ```
    A) Hello
    B) World
    C) Hello World
    D) None

16. How can you make a function return multiple values?
    A) Use multiple return statements
    B) Return a tuple, list, or dictionary
    C) Use the yield keyword multiple times
    D) It's not possible in Python

17. What is the purpose of the 'global' keyword in a function?
    A) To create a new global variable
    B) To use a global variable inside the function
    C) To prevent the function from accessing global variables
    D) To make all variables in the function global

18. What is the output of this recursive function?
    ```python
    def factorial(n):
        if n == 0:
            return 1
        return n * factorial(n-1)
    
    print(factorial(3))
    ```
    A) 3
    B) 6
    C) 9
    D) Error (infinite recursion)

19. Which of the following is not a valid function definition?
    A) def f():
    B) def f(a, b, c):
    C) def f(*args):
    D) def f(a, b, c,):

20. What is the output of this code?
    ```python
    def outer():
        x = "local"
        def inner():
            nonlocal x
            x = "nonlocal"
        inner()
        print(x)
    
    outer()
    ```
    A) local
    B) nonlocal
    C) Error
    D) None

21. What is a lambda function in Python?
    A) A function defined using the 'lambda' keyword
    B) A function that always returns True or False
    C) A function that can only have one argument
    D) A function that is automatically called at program start

22. What is the output of this code?
    ```python
    def increment(n):
        return n + 1
    
    result = increment(5)
    print(result)
    ```
    A) 5
    B) 6
    C) None
    D) Error

23. Which of the following is true about function arguments in Python?
    A) All arguments must have default values
    B) Functions can have a variable number of arguments
    C) Arguments are always passed by reference
    D) Functions can have a maximum of 5 arguments

24. What does the asterisk (*) do in a function definition?
    A) It makes the function recursive
    B) It allows the function to accept any number of positional arguments
    C) It multiplies the return value by 2
    D) It makes all arguments optional

25. What is the output of this generator function?
    ```python
    def countdown(n):
        while n > 0:
            yield n
            n -= 1
    
    for i in countdown(3):
        print(i, end=' ')
    ```
    A) 1 2 3
    B) 3 2 1
    C) 3 3 3
    D) Error

Answers:
1. B, 2. A, 3. B, 4. C, 5. B, 6. A, 7. B, 8. A, 9. B, 10. B, 11. C, 12. C, 13. B, 14. A, 15. A, 16. B, 17. B, 18. B, 19. D, 20. B, 21. A, 22. B, 23. B, 24. B, 25. B