Control Flow, Range Operators & Exhaustive Switch

Closed ranges ..., half-open ranges ..<, tuple matching, and where clauses

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Swift provides control flow with range operators (0...5 and 0..<5) and switch statements that must be 100% exhaustive.

Ranges & Advanced Switch Matching

Closed Range (1...5): Includes 1, 2, 3, 4, and 5.

Half-Open Range (1..<5): Includes 1, 2, 3, 4 (excludes 5), ideal for zero-indexed array counts.

No Fallthrough: Swift switch cases do not fall through to the next case by default, eliminating break statements.

where clauses: Adds conditional logic directly into switch pattern matching.

Pattern Matching with Switch and Ranges

Try It Yourself »

let examScore = 88

let letterGrade: String
switch examScore {
case 90...100:
    letterGrade = "A"
case 80..<90:
    letterGrade = "B"
case 70..<80:
    letterGrade = "C"
default:
    letterGrade = "Needs Improvement"
}

print("Final Grade: \(letterGrade)") // Final Grade: B

Ranges seamlessly map to switch evaluation cases.

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Test Yourself With Exercise

+15 XP

Which range operator in Swift creates a half-open range from `a` up to (but not including) `b`?

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