Swift Basics-4

Function: A block of code that completes a specific task, by name, to indicate what the function does

Func function name (formal parameter: parameter type)--return type

Command +option+0 hide the box to the right

Defining functions

func SayHello (name:string),string{

let greeting = "Hello" + name + "!"

return Greeting

}

println(sayHello("Anno"))

// multiple parameters

func minusresult (start:int, end:int),int{

return End-start

}

println(minusresult(1,ten))

// no parameters

func SayHelloWorld (),String{

return "Helo World"

}

println(sayhelloworld())

// no return value Void = empty tuple (tuple)

func Saygoodbye (name:String) {

println("Goodby,\ (name)")

}

println(saygoodbye("Dave"))

// multiple return value functions

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")

/// external parameter name to connect two strings together

func Join (S1:string, s2:string, Joiner:string),string{

return s1 + joiner + s2

}

println(join("Hello","World", ","))

// do not use external parameters, these three parameters are not clear what exactly is the

func joins (outsting S1:string, tosting s2:string, Withjoiner joiner:string), String{

return s1 + joiner + s2

}

println(joins(outsting: "hello", tosting:"World", Withjoiner:","))

// problem: When calling a function , write too much, the solution to see below

// shorthand external parameter name parameter name plus #

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)

// to default parameters

func joinss (outsting s1:string, tosting s2:string, Withjoiner joiner:string = ","),String{

return s1 + joiner + s2

}

//The third parameter is not written directly using default values

let str1 = joinss(outsting: "Nihao", tosting: "Heri")

println(str1)

// attention will go wrong

func joinbb (outsting s1:string, tosting s2:string, Withjoiner joiner:string = "" ),String{

return s1 + joiner + s2

}

//The third parameter is not written directly using default values

let str2 = joinbb(outsting: " haha", tosting: " zheli", Withjoiner: "+") /c9>

println(str2)

// variable parameter passed in an indeterminate number to enter the parameter variable name type ... = array constant

Swift Basics-4