Object-oriented Python and projects · 15 MIN

Build a command-line expense tracker

Create a menu-driven expense tracker that accepts a description, amount and category. Store records in JSON or CSV, calculate totals by category and handle invalid input. Separate input/output from calculation functions so the logic can be tested.

Try it yourself

Change the example, run it, and explain the result in your own words. Then create one variation of your own.

Key idea

Use the example as a starting point, not something to memorize. Practise, inspect the result and make small improvements.

Code example

expenses = []
def add_expense(description, amount):
    if amount <= 0:
        raise ValueError("Amount must be positive")
    expenses.append({"description": description, "amount": amount})

add_expense("Internet", 12000)
print(sum(item["amount"] for item in expenses))

Practise this lesson