Sets Mini Project — Attendance Tracker

What you're building

An attendance tracker. You have a fixed list of enrolled students. The user marks who showed up. At the end — present, absent, numbers.

What you need to know first

• Sets — creating, add(), in
• Set operations — difference, intersection
• while True with break
• input()
• len()

The brief

Build a program that:

• Starts with a fixed set of enrolled students
• Starts with an empty set for present students
• Loops — user types a name to mark as present, or done to finish
• Warns if the name isn't on the enrolled list
• Warns if the student was already marked present
• At the end: prints present students, absent students, and counts

Think before you code

• How do you check if a name is enrolled before marking them present?
• How do you find who was absent — students enrolled but not present?
• How do you avoid marking someone present twice?

Your starting point

enrolled = {"Raven", "Wolf", "Ghost", "Viper", "Bull"}
present  = set()

while True:
    name = input("Mark present (or 'done'): ").capitalize()

    if name == "Done":
        break

    # your code here

# print summary here

Expected output

Mark present (or 'done'): Raven
Raven marked present.
Mark present (or 'done'): Wolf
Wolf marked present.
Mark present (or 'done'): Fox
Fox is not on the enrolled list.
Mark present (or 'done'): Raven
Raven is already marked present.
Mark present (or 'done'): done

--- Attendance Report ---
Present (3): Bull, Ghost, Raven, Wolf
Absent  (2): Bull, Viper
Total enrolled: 5

Heads up!

• Use in to check enrollment before adding to present
• Use in again to check if already marked present
• Absent students = enrolled - present — one line with set difference
• Sets are unordered — sort before printing for clean output

The solution

enrolled = {"Raven", "Wolf", "Ghost", "Viper", "Bull"}
present  = set()

while True:
    name = input("Mark present (or 'done'): ").capitalize()

    if name == "Done":
        break
    elif name not in enrolled:
        print(f"{name} is not on the enrolled list.")
    elif name in present:
        print(f"{name} is already marked present.")
    else:
        present.add(name)
        print(f"{name} marked present.")

absent = enrolled - present

print("\n--- Attendance Report ---")
print(f"Present ({len(present)}): {', '.join(sorted(present))}")
print(f"Absent  ({len(absent)}): {', '.join(sorted(absent))}")
print(f"Total enrolled: {len(enrolled)}")