Default Parameters

// DEFAULT PARAMETER VALUES
// Provide a fallback value if caller doesn't specify

func greet(name: String = "Guest") {
    print("Hello, \(name)!")
}

greet()              // Hello, Guest!
greet(name: "Alice") // Hello, Alice!

// MULTIPLE DEFAULT PARAMETERS
func createUser(
    name: String,
    age: Int = 0,
    country: String = "Unknown",
    isAdmin: Bool = false
) {
    print("Name: \(name)")
    print("Age: \(age)")
    print("Country: \(country)")
    print("Admin: \(isAdmin)")
}

// Call with all defaults
createUser(name: "Bob")

// Override some defaults
createUser(name: "Charlie", age: 25)
createUser(name: "David", country: "USA")
createUser(name: "Eve", isAdmin: true)

// Override all
createUser(name: "Frank", age: 30, country: "UK", isAdmin: true)

// PRACTICAL EXAMPLES

// 1. HTTP Request with defaults
func request(
    url: String,
    method: String = "GET",
    timeout: Int = 30
) {
    print("\(method) \(url) (timeout: \(timeout)s)")
}

request(url: "https://api.example.com")
request(url: "https://api.example.com", method: "POST")
request(url: "https://api.example.com", method: "PUT", timeout: 60)

// 2. Print with separator
func printItems(_ items: String..., separator: String = ", ") {
    print(items.joined(separator: separator))
}

printItems("Apple", "Banana", "Cherry")
printItems("A", "B", "C", separator: " - ")

// 3. Game settings
func startGame(
    difficulty: String = "Normal",
    players: Int = 1,
    soundEnabled: Bool = true
) {
    print("Starting \(difficulty) game with \(players) player(s)")
    print("Sound: \(soundEnabled ? "ON" : "OFF")")
}

startGame()
startGame(difficulty: "Hard")
startGame(difficulty: "Easy", players: 2, soundEnabled: false)

// DEFAULT VALUES EVALUATED AT CALL TIME
var counter = 0
func getNextID(prefix: String = "ID-\(counter)") -> String {
    counter += 1
    return prefix
}