Code Labs: Subprogrammes

Master Procedures, Functions, Parameters, and Returning Data.

Interactive Engine

Use the interactive terminal below to test Functions and Parameters.

functions_demo.py

# 1. Defining a Function with Parameters
def add_scores(score1, score2):
    total = score1 + score2
    return total

# 2. Calling the function
result = add_scores(50, 25)

# 3. Outputting the returned value
print("The returned total is:", result)

Console Output

> Waiting to compile...

The Crucible

Prove your knowledge of creating and calling subprogrammes.

Bronze (Procedure calls)

The Initiator

Defining a procedure does absolutely nothing until you Call it.

Task: In the main code section below the definition, call the greet_user() procedure and pass your own name as a string parameter. For example, greet_user("Alan").

bronze.py

def greet_user(name):
    print("System booting up...")
    print("Welcome back,", name)

# Your code below: Call the procedure!

> Output will appear here...

Silver (Parameters)

Missing Data

The function calculate_area is meant to multiply a width and a height, but the programmer forgot to define the parameters in the brackets! They also only passed one number when calling it.

Task: 1) Put width, height inside the function definition brackets. 2) Provide a second number when calling the function.

silver.py

# Fix the parameters here:
def calculate_area():
    area = width * height
    print("The area is:", area)

# Fix the function call here (it needs two numbers!):
calculate_area(10)

> Output will appear here...

Gold (Return Values)

The Return Command

A true Function does not print things itself! It performs its job invisibly and uses the return keyword to hand the calculation data back to the main programme.

Task: Change the print(discounted) command inside the function to use the return keyword instead. E.g., return discounted. The main programme will handle the printing.

gold.py

def apply_discount(price, discount_amount):
    discounted = price - discount_amount
    # change this print to a return statement!
    print(discounted)

# ------------- Main Program -------------
final_price = apply_discount(100, 20)
print("Checking out... Final price is: £", final_price)

> Output will appear here...

Return to Theory Guide

Interactive Engine

User Input Required

The Initiator

Missing Data

The Return Command