Python - Return of The Function

CH06.05 - Functions: Return Values (Multiple)

Can Functions Return Multiple Things?

A function doesn’t have to return just one value. It can return several using a tuple or list.
This is useful when:
- - A function does a complex calculation.
  - You need different pieces of related information.
  - You want to reduce the number of function calls and keep your code clean.

What's This TUPLE Thing Again??

Remember This... a tuple is just a list (that you can't change!!)

We will deal with tuples a lot more, but for now, you just need to know that a tuple is essentially a list, which we can't change the values of
We access these the EXACT SAME WAY we access a list too!

import random

#This is a function which rolls a pair of dice

def roll_2_dice(numSides):

r1 = random.randint(1, numSides)

r2 = random.randint(1, numSides)

return r1, r2

# Since the function returns 2 things, I need to place

# the values in 2 variables! This is called UNPACKING

d1, d2 = roll_2_dice(6)

print(f"Your First Die was: {d1}")

print(f"Your Second Die was: {d2}")

How does it work?

roll_2_dice() takes 1 parameter, the number of sides of a die
- - it will roll 2 times, and store those values in r1 and r2
Since 2 things are returned, we need to UNPACK THOSE VALUES into 2 SEPARATE VARIABLES which are COMMA SEPARATED and IN-ORDER
We can then use those as we see fit

Do you only return 2 things in a tuple?

No. We can return as MANY THINGS AS WE WANT using this

Example:

def get_hero( ):fn = "Bruce"ln = "Wayne"alias = "Batman"superpower = "Being Rich"return fn, ln, alias, superpower #Unpack the Tuple Returned:first, last, heroname, spower = get_hero()print(f"{first} {last} is {heroname} and is power is {spower}")

🛠️ Phineas and Ferb: Inator Creator! 🔬

Dr. Doofenshmirtz is building a brand-new -inator device! But he needs help coming up with the name, function, and unexpected side effects. Students will write a function that randomly generates a new invention, returning multiple values (name, purpose, and side effect).

📌 How It Works:

1️⃣ The create_inator() function randomly selects a name, purpose, and side effect.

2️⃣ It returns these three values as a tuple.

3️⃣ The main program unpacks the tuple into three variables (name, purpose, effect).

4️⃣ It then prints out the hilarious invention and its unintended consequences.

Sample Output

Remember, the NAME of the Inator, Purpose, and Side Effect are all stored in the create_inator() function
You have to get one of each of them randomly
The function returns the tuple to be unpacked

🚀 Real-World Example: Weather System

Your Goal:

Weather data often comes with multiple related values. Returning them as a tuple lets you pass around a full snapshot of the forecast, which can be unpacked and used for display, analysis, or alerts without extra fuss.

Your Goal:

You want to write a function called get_weather() that will return:
- - City Name
    - - Determined from a random list:
      - BONUS: Write a function called get_city() which returns a city to get_weather()
  - Temperature
    - - Generated Randomly from an appropriate set of values
      - BONUS: Write a function called get_temp() which will return a temperature to get_weather()
  - Weather Condition
    - - Determined from a random list:
      - BONUS: Write a function called get_condition() which returns a weather condition to get_weather()
        Sunny, Cloudy, Snowing, etc...
  - Wind Speed
    - - Generated Randomly from an appropriate set of values
      - BONUS: Write a function called get_wind() which will return a temperature to get_weather()
Write a function called format_weather(city, temp, condition, wspeed) which
- - Formats the weather report in a pleasing manner

Additionally, you need to ask the user if they want to see the weather for another city, and stop when they say no
- - BONUS: Don't show the same city information more than once!!!
    - - This is trickier than you think...

🚀 Real-World Example: Online Shopping System 🛒

Now, lets look at how this is used in the real-world! A real-world application of functions returning values can be seen in an online shopping system. This program simulates a checkout system where:

✅ One function prints a receipt (no return)

✅ One function returns a single value (calculates tax)

✅ Two functions return multiple values (process an item & checkout total)

📌 How It Works:

1️⃣ print_receipt_header() – Prints the store header (No return).

2️⃣ calculate_tax() – Calculates 8% tax on the total purchase (Single return).

3️⃣ process_item() – Selects a random product and its price (Multiple return).

4️⃣ checkout() – Generates 1-5 random items, calculates the subtotal, and returns the cart + total cost (Multiple return).

What You Should Try And Do:

🔹 Task 1: Print the Store Header (No Return Function)

Create a function that prints a welcome message and a decorative receipt header.
This function does not return anything, it just displays information.

🔹 Task 2: Calculate Sales Tax (Single Return Function)

Create a function that takes the subtotal as an argument.
Calculate the tax (8% of the subtotal).
Return the tax amount to be added to the total price.

🔹 Task 3: Process a Single Item (Multiple Return Values)

Create a function that selects a random item from a list of products.
The function should also select the corresponding price of the item.
Return both the item name and its price.

🔹 Task 4: Checkout Process (Multiple Return Values)

Create a function that:
Selects 1 to 5 random items using the function from Task 3.
Stores the items and their prices in a list (or similar structure).
Calculates the subtotal of all selected items.
Returns the list of purchased items and the subtotal.

🔹 Task 5: Display Final Receipt

Call the functions in the correct order:
- - Print the receipt header.
  - Run the checkout process to get purchased items and subtotal.
  - Calculate the tax using the subtotal.
  - Display all items purchased, subtotal, tax, and final total in a well-formatted receipt.

Now Onto The Big Programs!!

Catapult Attack

Scrooge McDuck Treasure Hunt

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