Filter and sum integer money

Your task

Calculate sales only from completed orders, retaining the raw file. Explain the expected output before running the code.

Hint

Read with csv.DictReader so column names are explicit. CSV values are strings until converted. Keep parsing failures visible.

Worked solution

Output 700.0 EUR. Sum integer cents before converting for display. This prevents cumulative binary rounding of currency inputs.

import csv
with open('retail-orders.csv',newline='',encoding='utf-8') as f:
    rows=list(csv.DictReader(f))
done=[r for r in rows if r['status']=='completed']
cents=sum(int(r['net_cents']) for r in done)
assert cents==70000
print(cents/100)

Extend the test

Change one input in a disposable copy and predict which check should fail. Restore the original before comparing results.

Make the reasoning yours.

Try the activity before reading its reference. Keep your sources, commands and assumptions with your work. Companion activities are unsaved self-practice and do not award a certificate or change lesson progress.