BSc IT - Programming in Python

Top-down design  is a method of solving complex problems by breaking them into smaller, more manageable sub-problems. In programming, especially when working with modules, this approach helps organize code by starting with the main task and then dividing it into functions or sub-modules. 

In this design, you first define the overall goal of the program or module. Then, you break it down into smaller parts (functions or components), each responsible for a specific task. These parts can be further divided if needed, making the development process easier and more structured.

# main.py - Using our module with top-down design

import bill_calculator

subtotal = float(input("Enter the food cost: "))
total = bill_calculator.total_bill(subtotal)

print("Total bill with tax and tip: $", round(total, 2))

# Module: bill_calculator.py

def calculate_tax(amount):
    return amount * 0.10

def calculate_tip(amount):
    return amount * 0.15

def total_bill(subtotal):
    tax = calculate_tax(subtotal)
    tip = calculate_tip(subtotal)
    return subtotal + tax + tip