本博客笔记内容：@H_502_1@

函数定义与调用（Defining and Calling Functions）@H_502_1@

函数参数与返回值（Function Parameters and Return Values）@H_502_1@

函数参数名称（Function Parameter Names）@H_502_1@

直接上代码：代码有注释：@H_502_1@

//: Playground - noun: a place where people can play@H_502_1@

import UIKit@H_502_1@

//定义一个带参数的函数@H_502_1@

// \()是用来替换变量值@H_502_1@

func sayHello(personName: String ) -> String {@H_502_1@

let greeting = "Hello,\(personName)"@H_502_1@

return greeting@H_502_1@

}@H_502_1@

//调用函数，函数名和参数@H_502_1@

print(sayHello("luopan"))@H_502_1@

//定义一个无参数的函数@H_502_1@

func sayHello() ->String {@H_502_1@

return "hello,swift!"@H_502_1@

}@H_502_1@

//调用函数，函数名@H_502_1@

print(sayHello())@H_502_1@

//定义一个多参数的函数@H_502_1@

func sayHello(personName:String,alreadyGreed:Bool)->String{@H_502_1@

if alreadyGreed{@H_502_1@

return sayHello("第二次\(personName)")@H_502_1@

}else{@H_502_1@

return sayHello("第一次\(personName)")@H_502_1@

}@H_502_1@

}@H_502_1@

print(sayHello("luopan",alreadyGreed: false))@H_502_1@

print(sayHello("luopan",alreadyGreed: true))@H_502_1@

//定义返回元祖，从而达到返回多个值的效果@H_502_1@

func minMax(array:[Int]) -> (min:Int,max:Int){@H_502_1@

var currentMin = array[0]@H_502_1@

var currentMax = array[0]@H_502_1@

for value in array[1..<array.count]{@H_502_1@

if value < currentMin {@H_502_1@

currentMin = value@H_502_1@

}else if value > currentMax{@H_502_1@

currentMax = value@H_502_1@

}@H_502_1@

}@H_502_1@

return (currentMin,currentMax)@H_502_1@

}@H_502_1@

let bounds = minMax([6,-2,4,456,3,78])@H_502_1@

print("min is \(bounds.min) and max is \(bounds.max)")@H_502_1@

//定义可选性元祖作为返回@H_502_1@

func minMax(array:[Double]) -> (min:Double,max:Double)?{@H_502_1@

var currentMin = array[0]@H_502_1@

var currentMax = array[0]@H_502_1@

@H_502_1@

for value in array[1..<array.count]{@H_502_1@

if value < currentMin {@H_502_1@

currentMin = value@H_502_1@

}else if value > currentMax{@H_502_1@

currentMax = value@H_502_1@

}@H_502_1@

}@H_502_1@

return(currentMin,currentMax)@H_502_1@

}@H_502_1@

//那么我们使用的时候需要解包可选型@H_502_1@

if let minMaxValue = minMax([23.34,-34,78,45.56,545.00,333.444]){@H_502_1@

print("min is \(minMaxValue.min) and max is \(minMaxValue.max)")@H_502_1@

}@H_502_1@

//定义一个具有外部参数名和局部变量名的函数@H_502_1@

func sayHello(to person:String,and anotherPerson:String) ->String{@H_502_1@

return "Hello \(person) and \(anotherPerson)"@H_502_1@

}@H_502_1@

//注意，如果指定了外部参数变量名，那么调用的时候，必须带上的。@H_502_1@

print(sayHello(to: "luopan",and: "mingxing"))@H_502_1@

//定义一个可变参数个数的函数@H_502_1@

func arithmeticMean(numbers:Double...) -> Double{@H_502_1@

var total:Double = 0@H_502_1@

for number in numbers{@H_502_1@

total += number@H_502_1@

}@H_502_1@

@H_502_1@

return total/Double(numbers.count)@H_502_1@

}@H_502_1@

//注意一个函数只能有一个可变参数@H_502_1@

print(arithmeticMean(1,2,5))@H_502_1@

print(arithmeticMean(3,8.26,18.75))@H_502_1@

今天到此为止吧！@H_502_1@