스위프트 함수 스코프 swift function return scope

/*

 함수 : 특정 작업을 수행하는 독립적인 코드 덩어리

 

 예)

 커피 내리기

 1. 물을 끓인다.

 2. 커피 공을 간다.

 3. 필터에 넣고 물을 흘려보낸다.

 4. 커피를 따뜻하게 유지시킨다.

 ...

 

 DRY : Don't Repeat Yourself

 */

// Wall #1

let width = 25

let height = 7

let area = width * height

// Wall #2

let secondWidth = 14

let secondHeight = 3

let secondArea = secondWidth * secondHeight

func calculateArea() {

    let width = 25

    let height = 7

    let area = width * height

    print(area)

}

calculateArea() // 175

func calculateArea2(width: Int) {

    let height = 7

    let area = width * height

    print(area)

}

calculateArea2(width: 10) // 70

calculateArea2(width: 20) // 140

func calculateArea3(width: Int, height: Int ) {

    let area = width * height

    print(area)

}

// Wall #3

calculateArea3(width: 17, height: 10) // 170

// Wall #4

calculateArea3(width: 14, height: 3) // 42

func calculaterArea4(width: Int ,height: Int ) -> Int {

    let area = width * height

    return area

}

let areaOfWall1 = calculaterArea4(width: 17, height: 10)

// Hint : Double

// C = (F-32) * 5/9

func convertToCelsius (temperature: Double ) -> Double {

    let temperatureInCelsius = (temperature - 32) * 5/9

    return temperatureInCelsius

}

let C = convertToCelsius(temperature: 80)

print(C) // 26.6666666666667

func convertToCelsius2 (temperatureInFahrenheit temp: Double ) -> Double {

    let temperatureInCelsius = (temp - 32) * 5/9

    return temperatureInCelsius

}

convertToCelsius2(temperatureInFahrenheit: 80)

func sayHello(to person: String, and anotherPerson: String) -> String {

    return "Hello \(person) and \(anotherPerson)"

}

sayHello(to: "Jack", and: "Jill")

let sayHello1 = sayHello(to: "Jack", and: "Jill")

print(sayHello1) // "Hello Jack and Jill\n"

func calculateWallpaperPrice(area: Int , color: String) -> Int {

    var price: Int

    switch color {

    case "beige": price = area * 10000

    case "gray": price = area * 15000

    case "pink": price = area * 20000

    default: price = 0

    }

    return price

}

// 함수 areaOfWall1 를 호출해서 area에 넣어준다.

calculateWallpaperPrice(area: areaOfWall1, color: "beige")

func calculateWallpaperPrice2 (width: Int ,height: Int  , color: String) -> Int {

    var price: Int

    

    let area = calculaterArea4(width: width, height: height)

    

    switch color {

    case "beige": price = area * 10000

    case "gray": price = area * 15000

    case "pink": price = area * 20000

    default: price = 0

    }

    return price

}

calculateWallpaperPrice2(width: 17, height: 10, color: "beige")

func calculateWallpaperPrice3 (width: Int ,height: Int  , color: String = "beige" ) -> Int {

    var price: Int

    

    let area = calculaterArea4(width: width, height: height)

    

    switch color {

    case "beige": price = area * 10000

    case "gray": price = area * 15000

    case "pink": price = area * 20000

    default: price = 0

    }

    return price

}

// 함수의 파라미터 기본값을 설정하면 아래와 같이 2개 값만 입력 가능하게 나온다.

//calculateWallpaperPrice3(width: <#T##Int#>, height: <#T##Int#>)

//calculateWallpaperPrice3(width: <#T##Int#>, height: <#T##Int#>, color: <#T##String#>)

calculateWallpaperPrice3(width: 15, height: 10) // 1500000

func calculateWallpaperPrice4 (width: Int ,height: Int  , color: String = "beige" ) -> (Int, String) {

    var price: Int

    

    let area = calculaterArea4(width: width, height: height)

    

    switch color {

    case "beige": price = area * 10000

    case "gray": price = area * 15000

    case "pink": price = area * 20000

    default: price = 0

    }

    return (price,color)

}

let result = calculateWallpaperPrice4(width: 14, height: 13)  // (.0 1820000, .1 "beige")

print(result) // "(1820000, "beige")\n"

print(result.0) // "1820000\n"

print(result.1) // "beige\n"

func calculateWallpaperPrice5 (width: Int ,height: Int  , color: String = "beige" ) -> (price: Int, color: String) {

    var price: Int

    

    let area = calculaterArea4(width: width, height: height)

    

    switch color {

    case "beige": price = area * 10000

    case "gray": price = area * 15000

    case "pink": price = area * 20000

    default: price = 0

    }

    return (price,color)

}

let result2 = calculateWallpaperPrice5(width: 12, height: 11) // (price 1320000, color "beige")

print(result2.price) // "1320000\n"

print(result2.color) // "beige\n"

// 함수 스코프 scope

func incrementAndDecrement(a: Int) {

    var a = a

    var b = a

    

    a += 1

    b -= 1

}

let a = 20

incrementAndDecrement(a: 20)

a // 20