Exercise

Python Functions and Scope

These exercises are designed to help you practice working with functions and scope in Python. Follow each step carefully and try to predict the output before running the code.

File Organization

We'll add a new directory called functions_and_scope to your existing file structure. The updated structure will look like this:

csf101-python_exercises/
│
├── basics/
│   ├── numbers.py
│   ├── strings.py
│   └── booleans.py
│
├── data_structures/
│   ├── lists.py
│   └── dictionaries.py
│
├── operators/
│   ├── arithmetic.py
│   ├── assignment.py
│   ├── comparison.py
│   ├── logical.py
│   └── bitwise.py
│
├── control_structures/
│   ├── conditionals.py
│   ├── loops.py
│   └── break_continue.py
│
└── functions_and_scope/
    ├── basic_functions.py
    ├── parameters_and_returns.py
    ├── scope.py
    └── recursion.py

Create a new directory called functions_and_scope inside your csf101-python_exercises directory.

Exercise 1: Basic Functions

File: functions_and_scope/basic_functions.py

Create a new file called basic_functions.py in the functions_and_scope directory and complete the following exercises in this file.

  1. Write a function called greet that prints "Hello, World!".

    def greet():
    print("Hello, World!")

greet()

    Expected output: Hello, World!

  2. Modify the greet function to take a name parameter and greet that person.

    def greet(name):
    print(f"Hello, {name}!")

greet("Alice")

    Expected output: Hello, Alice!

  3. Write a function called square that takes a number and returns its square.

    def square(number):
    return number ** 2

result = square(5)
print(result)

    Expected output: 25

  4. Create a function called is_even that takes a number and returns True if it's even, False otherwise.

    def is_even(number):
    return number % 2 == 0

print(is_even(4))
print(is_even(7))

    Expected output:

    True
False

  5. Write a function called print_numbers that prints numbers from 1 to n (inclusive).

    def print_numbers(n):
    for i in range(1, n + 1):
        print(i)

print_numbers(5)

    Expected output:

    1
2
3
4
5

Exercise 2: Parameters and Return Values

File: functions_and_scope/parameters_and_returns.py

Create a new file called parameters_and_returns.py in the functions_and_scope directory and complete the following exercises in this file.

  1. Write a function called greet_with_default that takes a name parameter with a default value of "Guest".

    def greet_with_default(name="Guest"):
    print(f"Hello, {name}!")

greet_with_default()
greet_with_default("Bob")

    Expected output:

    Hello, Guest!
Hello, Bob!

  2. Create a function called calculate_rectangle_area that takes width and height as parameters and returns the area.

    def calculate_rectangle_area(width, height):
    return width * height

area = calculate_rectangle_area(5, 3)
print(f"The area of the rectangle is: {area}")

    Expected output: The area of the rectangle is: 15

  3. Write a function called print_info that takes any number of keyword arguments and prints them.

    def print_info(**kwargs):
    for key, value in kwargs.items():
        print(f"{key}: {value}")

print_info(name="Alice", age=30, city="New York")

    Expected output:

    name: Alice
age: 30
city: New York

  4. Create a function called min_max that takes a list of numbers and returns both the minimum and maximum values.

    def min_max(numbers):
    return min(numbers), max(numbers)

result = min_max([5, 2, 8, 1, 9])
print(f"Min: {result[0]}, Max: {result[1]}")

    Expected output: Min: 1, Max: 9

  5. Write a function called safe_divide that takes two numbers and returns their division, or returns "Cannot divide by zero" if the second number is 0.

    def safe_divide(a, b):
    if b == 0:
        return "Cannot divide by zero"
    return a / b

print(safe_divide(10, 2))
print(safe_divide(5, 0))

    Expected output:

    5.0
Cannot divide by zero

Exercise 3: Scope

File: functions_and_scope/scope.py

Create a new file called scope.py in the functions_and_scope directory and complete the following exercises in this file.

  1. Demonstrate the difference between local and global variables.

    x = 10  # Global variable

def print_x():
    x = 20  # Local variable
    print(f"Local x: {x}")

print_x()
print(f"Global x: {x}")

    Expected output:

    Local x: 20
Global x: 10

  2. Modify a global variable from within a function.

    count = 0

def increment():
    global count
    count += 1
    print(f"Count: {count}")

increment()
increment()
print(f"Final count: {count}")

    Expected output:

    Count: 1
Count: 2
Final count: 2

  3. Create a function that uses a nonlocal variable.

    def outer():
    x = "outer"

    def inner():
        nonlocal x
        x = "inner"
        print(f"Inner x: {x}")

    inner()
    print(f"Outer x: {x}")

outer()

    Expected output:

    Inner x: inner
Outer x: inner

Exercise 4: Recursion

File: functions_and_scope/recursion.py

Create a new file called recursion.py in the functions_and_scope directory and complete the following exercises in this file.

  1. Write a recursive function to calculate the factorial of a number.

    def factorial(n):
    if n == 0 or n == 1:
        return 1
    else:
        return n * factorial(n - 1)

print(factorial(5))

    Expected output: 120

  2. Create a recursive function to generate the nth Fibonacci number.

    def fibonacci(n):
    if n <= 1:
        return n
    else:
        return fibonacci(n - 1) + fibonacci(n - 2)

print(fibonacci(7))

    Expected output: 13

Congratulations!

Remember to run each file separately to see the output of your exercises. You can do this by navigating to the appropriate directory in your terminal and running python filename.py (e.g., python basic_functions.py).