函数：完成特定任务的代码块，通过名字来表示函数做什么
func 函数名（形参：形参类型）->返回类型
command +option+0 隐藏右边的框
//定义函数
func sayHello(name:String)->String{
let greeting = "hello " + name + "!"
return greeting
}
println(sayHello("Anno"))
// 多个参数
func minusResult(start:Int,end:Int)->Int{
return end - start
}
println(minusResult(1,10))
//无参数
func sayHelloWorld() ->String{
return "Helo World"
}
println(sayHelloWorld())
// 无返回值 Void = 空元组（tuple）
func sayGoodbye(name:String){
println("Goodby,(name)")
}
println(sayGoodbye("Dave"))
// 多重返回值函数
func count(str:String) ->(vs:Int,cs:Int,os:Int){
var vowels = 0,consonants = 0,others = 0
for Character in str{
switch String(Character).lowercaseString{
case "a","e","i","o","u":
++vowels
case "b","c","d","f","g","h","j","k","l","m","n","p","q","t","s","t","v","w","x","y","z":
++consonants
default:
++others
}
}
return (vowels,consonants,others)
}
let total = count("some arbitrary string!")
println("(total.vs) vowels and (total.cs) consonants")
// 外部参数名 把两个字符串连在一起
func join(s1:String, s2:String,joiner:String) ->String{
return s1 + joiner + s2
}
println(join("hello","world",","))
// 不使用外部参数的时候，这三个参数不清楚到底是干什么的
func joins(outSting s1:String,toSting s2:String, withJoiner joiner:String) ->String{
return s1 + joiner + s2
}
println(joins(outSting:"hello",toSting:"world",withJoiner:","))
// 带来问题：调用函数的时候 写太多，解决办法 看下边
// 简写 外部参数名 参数名前 加#
// func joins1(outSting s1:String,toSting s2:String, withJoiner joiner:String) ->String{
// return s1 + joiner + s2
// }
// println(joins1(outSting:"hello",toSting:"world",withJoiner:","))
func containsCharacter(#string:String,#characterToFind:Character) ->Bool{
for character in string{
if character == characterToFind{
return true
}
}
return false
}
let containsAVee = containsCharacter(string: "qwertyuiop", characterToFind: "y")
println(containsAVee)
// 给默认参数
func joinss(outSting s1:String,toSting s2:String, withJoiner joiner:String = ",") ->String{
return s1 + joiner + s2
}
// 第三个参数 没写 直接使用默认值
let str1 = joinss(outSting: "nihao", toSting: "heri")
println(str1)
// 注意会出错
func joinbb(outSting s1:String,toSting s2:String, withJoiner joiner:String = "") ->String{
return s1 + joiner + s2
}
// 第三个参数 没写 直接使用默认值
let str2 = joinbb( outSting: "haha", toSting: "zheli", withJoiner: "+")
println(str2)
// 可变参数 传入不确定数量来输入参数 变量名类型 ... = 数组常量