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Functions & basics

Reusable building blocks — parameters, returns, scope, and clear function design.

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How to use function defaults in Python

Define Python functions with default parameter values so callers can omit arguments and use sensible fallbacks.

def greet(name="Guest", greeting="Hello", punctuation="!"):
    """Return a greeting message using default parameters."""
    return f"{greeting}, {name}{punctuation}"

def describe_pet(pet_name, animal_type="dog"):
    """Display information about a pet with a default animal type."""
    print(f"I have a {animal_type…

15 0 Open

Functions & basics easy

Mutual Recursion for Even/Odd Check in Python

Implements even and odd checks using two functions that call each other recursively, demonstrating base cases and alternating calls.

recursion functions mutual-recursion

Python

def is_even(n):
    if n == 0:
        return True
    return is_odd(n - 1)

def is_odd(n):
    if n == 0:
        return False
    return is_even(n - 1)

if __name__ == "__main__":
    for num in range(0, 11):
        print(f"{num}: even={is_even(num)}, odd={is_odd(num)}")

12 0 Open

Functions & basics easy

Python Function Default Parameters Explained with Examples

Learn how to define Python functions with default parameter values and call them with fewer arguments than declared.

functions default-parameters args

Python

def greet(name, greeting="Hello", punctuation="!"):
    return f"{greeting}, {name}{punctuation}"

def calculate_area(length, width=1, unit="sq units"):
    area = length * width
    return f"Area: {area} {unit}"

if __name__ == "__main__":
    print(greet("Alice"))
    print(greet("Bob", "Hi"))
    print(greet("Charl…

14 0 Open

Functions & basics easy

Write a Recursive Factorial Function in Python

Define a recursive factorial function that handles edge cases and returns the product of all positive integers up to n.

recursion factorial functions

Python

def factorial(n):
    """Return the factorial of n using recursion."""
    if n < 0:
        raise ValueError("Factorial is not defined for negative numbers")
    if n == 0 or n == 1:
        return 1
    return n * factorial(n - 1)

if __name__ == "__main__":
    print(factorial(5))

14 0 Open

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