Logical Operators: && || !

Workbook 1c, p.100 — Building compound conditions with AND, OR, and NOT

Operator Reference

AND

Both sides must be true for the result to be true

🚪🚪 Two doors in a hallway — both must be open to walk through.

At least one side must be true for the result to be true

🚪 🚪 Two separate exits — either one gets you out.

NOT

Flips true to false and false to true

💡 A light switch — flip it and the opposite happens.

Interactive Truth Tables — Toggle inputs and watch the result

Both must be true

false

false && false

Result: false

At least one must be true

false

false || false

Result: false

Flips the value

false

!false

Result: true

Real-World Scenario — Ticket Pricing

Age

isStudent

false

isMilitary

false

Common Mistakes

Watch out for these:

Single vs Double: Use && not & and || not |. The single versions are bitwise operators — they work differently and don't short-circuit.
Operator Precedence: && is evaluated before ||. So a || b && c means a || (b && c), not (a || b) && c. When in doubt, use parentheses to make your intent clear.
Double Negatives: !(!isActive) is just isActive. Keep conditions simple and readable.

Toggle the switches and move the slider to see how logical operators evaluate in real time.