Variadic Parameters

// VARIADIC PARAMETERS
// Accept any number of values of the same type

func sum(_ numbers: Int...) -> Int {
    var total = 0
    for number in numbers {
        total += number
    }
    return total
}

// Call with different amounts
print(sum(1, 2, 3))           // 6
print(sum(1, 2, 3, 4, 5))     // 15
print(sum(10))                // 10
print(sum())                  // 0 (empty is allowed)

// Inside the function, numbers is an [Int] array!

// PRACTICAL EXAMPLES

// 1. Print multiple items
func printAll(_ items: Any...) {
    for item in items {
        print(item)
    }
}
printAll("Hello", 42, true, 3.14)

// 2. Find average
func average(_ numbers: Double...) -> Double {
    guard !numbers.isEmpty else { return 0 }
    let sum = numbers.reduce(0, +)
    return sum / Double(numbers.count)
}
print(average(85, 90, 78, 92))  // 86.25

// 3. Build HTML class string
func classes(_ names: String...) -> String {
    return names.joined(separator: " ")
}
print(classes("btn", "btn-primary", "active"))
// "btn btn-primary active"

// COMBINING WITH OTHER PARAMETERS
// Variadic must come after regular parameters

func greet(title: String, names: String...) {
    for name in names {
        print("\(title) \(name)")
    }
}
greet(title: "Hello", names: "Alice", "Bob", "Charlie")

// WITH DEFAULT PARAMETERS
func log(level: String = "INFO", messages: String...) {
    for msg in messages {
        print("[\(level)] \(msg)")
    }
}
log(messages: "App started", "Loading data")
log(level: "ERROR", messages: "Failed to connect")

// LIMITATIONS
// Only one variadic parameter per function
// Variadic parameter is treated as an array inside

// REAL-WORLD: Custom print function
func debugLog(_ items: Any..., separator: String = " ") {
    let output = items.map { String(describing: $0) }
    print("[DEBUG]", output.joined(separator: separator))
}
debugLog("User:", "Alice", "Age:", 25)