Swift学习——使用if和switch来进行条件操作，使用for,while,和do-while来进行循环

//switch支持随意类型的数据以及各种比較操作——不不过整数以及測试相等

//注意假设去掉default程序会报错

let strings = "hello3"

switch strings{

    case "hello1":

    let stringsComment = "say hello1"

    println("stringsComment is \(stringsComment)")

    break

    case "hello2","hello3":

    let stringsComment = "say hello2 and hello3"

    println("stringsComment is \(stringsComment)")

    break

    case let x where x.hasSuffix("hello4"):

    let stringsComment = "Is it a spicy \(x)?

"

    println("stringsComment is \(stringsComment)")

    break

    default:

    let stringsComment = "say everything"

    println("stringsComment is \(stringsComment)")

}

简单的while和do-while循环

// while循环

var n = 3

while n < 100{

    n = n*2

}

println("n is \(n)")

//do-while循环

var m = 3

do{

    m = m*2

}while m < 100

println("m is \(m)")

打印结果

stringsComment is say hello2 and hello3

n is 192

m is 192