Swift -運算符和循環結構

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

 

import UIKit

 

var str = "Hello, playground"

 

//賦值符號

//var a = 3

 

//控制流 （順序結構， 循環結構， 選擇結構）

 

//循環結構

//for in

for i in -99...99 {

    i*i

}

 

 

var result = 1

var base = 2

var power = 10

for _ in 1...power {//_忽略值的使用

    result *= base

}

result

 

 

//for 循環

for var i = -99 ; i <= 99; i++ {//swift3 報錯

    i*i

}

 

 

//while 

 

var  aWin = 0

var  bWin = 0

var  game = 0

 

while aWin < 3 && bWin < 3 {

    game = game + 1

    

    let a  = arc4random_uniform(6) + 1

    let b  = arc4random_uniform(6) + 1

    print("a is \(a), b is \(b). ",  terminator: "")

    

    

    if a > b {

        print("A win")

        bWin = 0

        aWin = aWin + 1

    }

    else if a < b {

        print("B win")

        bWin = bWin + 1

        aWin = 0

    }

    else {

        print("draw")

        aWin = 0

        bWin = 0

    }

}

 

print("game is \(game)")

 

 

repeat - while 至少要執行一次循環

 

var aWin = false

var bwin = false

 

repeat {

    let a = arc4random_uniform(6) + 1

    let b = arc4random_uniform(6) + 1

    print("s is \(a), b is \(b).")

    if a > b {

        aWin = true

    }

    else if a < b {

        bwin = true

    }

    else {

        print("draw ")

    }

    print("")

    

}while !aWin && !bwin

 

let winner  = aWin ? "A" : "B"

print("\(winner) win !!")

 

 

//選擇結構

let poin = (0, 0)

 

switch poin {

case (0, 0):

    print("It is Origin")

    fallthrough//容許進入下一個判斷語法中

case (_, 0):

    print("It is on x-axis")

default:

    print("It is just an ordinary point")

}

 

// x^4 - y^2 = 15*x*y 求一組值

 

findAnswer:

for m in 1...300 {

    for n in 1...300 {

        if m*m*m - n*n == 15*m*n {

            print(m,n)

            break findAnswer

        }

    }

}

 

//while

 

let poin = (3,3)

switch poin {

case let (x, y) where x == y:

    print("It is On the line x == y")

case let (x, y) where x == -y:

    print("It is On the line x == -y")

default:

    print("It is a poin")

}

 

let age = 19

if case 10...19 = age {

    print("You are is a teenager !")

}