Operators

An operator is a symbol that works on values, like + or &&.

Arithmetic and assignment

+, -, *, /, %, plus compound assignment:

var score = 10
score += 5
score -= 2
score *= 2
print(score)

26

Swift has no ++ or -- operators — write score += 1.

Logical operators

let age = 20
let hasTicket = true

print(age >= 18 && hasTicket)
print(age < 13 || age > 65)
print(!hasTicket)

true
false
false

• && (and) — true only if both sides are true.
• || (or) — true if either side is true.
• ! (not) — flips true and false.

Swift stops evaluating as soon as the answer is known: in a && b, if a is false, b is never checked.

The ternary operator

condition ? valueIfTrue : valueIfFalse picks one of two values:

let temperature = 30
let advice = temperature > 25 ? "Wear a hat" : "Bring a jacket"
print(advice)

Wear a hat

Range operators

• 1...5 — a closed range: 1, 2, 3, 4, 5.
• 1..<5 — a half-open range: 1, 2, 3, 4 (excludes 5).

Ranges are used with loops and switch, covered in their own lessons.

Common mistakes

• Writing = (assignment) in a condition instead of ==. Swift refuses to compile if x = 5, which prevents a classic bug.

Practice

A shop gives free delivery if an order is over 50 or the customer is a member. With total = 42 and isMember = true, print whether delivery is free, using the ternary operator to print Free delivery or Delivery: $5.

let total = 42
let isMember = true
print(total > 50 || isMember ? "Free delivery" : "Delivery: $5")

Free delivery