Swift学习——函数、数组

//带返回值的函数
func greet(_ person: String, on day:String) -> String {
    let bb = "hello \(person) \(day)"
    print(bb)
    return bb
}

greet("小明", on: "2月3")

//返回值是元组的函数（多个返回值）
func duoGeFanHuiZhi(scores: [Int]) -> (min: Int, max: Int, sum: Int){
    var min = scores[0]
    var max = scores[0]
    var sum = 0
    
    for score in scores {
        if  score > max {
            max = score
        } else if score < min {
            min = score
        }
        sum += score;
    }
    return (min, max, sum)
}

let result = duoGeFanHuiZhi(scores: [3,4,5,33,44,666,232])

print(result.max)

//可变个数参数的函数
func keBianGeShuDeHanShu(numbers:Int...) -> Int {
    var sum = 0
    for number in numbers {
        sum += number;
    }
    return sum
}

keBianGeShuDeHanShu(numbers: 0)
keBianGeShuDeHanShu(numbers: 3, 4, 5)

//写一个计算平均值的函数
func calculateAverage(numbers: Int...) -> Int{
    var  sum = 0
    for number in numbers {
        sum += number
    }
    let count = numbers.count
    let average = sum / count
    return average
}

calculateAverage(numbers: 2, 4, 6)

//函数作为返回值
func makeIncrementer() -> ((Int) -> Int) {
    
    //被返回的函数
    func addOne(number: Int) -> Int {
        return 1 + number
    }
    return addOne
}
var increment = makeIncrementer()
increment(7)

//函数作为参数
func hasAnyMatches(list: [Int], condition:(Int) -> Bool) -> Bool {
    for item in list {
        if condition(item) {
            return true
        }
    }
    return false
}

func lessThanTen(number:Int) ->Bool{
    return number < 10
}

var numbers = [20,19,7,3]

hasAnyMatches(list: numbers, condition: lessThanTen)

numbers.map({
    (number: Int) -> Int in
    let result = 3 * number;
    return result
})

let allAddOne = numbers.map({number in number + 1})
print(allAddOne)

//数组排序
let sortedNumbers = numbers.sorted(){ $0 < $1 }
print(sortedNumbers)

//字符串数组
let strings:[String] = ["sss", "bbbbb", "cccccc"]
let a = "aaa"
//获取字符串长度
print(a.characters.count)
let sortedStrings = strings.sorted { (a, b) -> Bool in
    return a.characters.count > b.characters.count
}

let sortedStrings2 = strings.sorted(){$0.characters.count > $1.characters.count}
print(sortedStrings)
print(sortedStrings2)