Swfit 5.0 流程控制

1. if-else

• if 后面的条件只能是Bool类型, if 后面括号可以省略

 

var age : Int = 30
if age == 30 {
    print("my age is \(age)")
}

2. while

• while 后面需要时 bool 类型
• repeat-while 等同于 do-while

 

var count = 0
while count<=5 {
    print("num is \(count)")
    count += 1
}

count = 0
repeat {
    print("num is \(count)")
}while count>0

3. for-in

区间运算

• 闭区间运算符:a...b ,表示 a<= 取值 <=b
• 半开区间运算符:a..<b， a <= 取值 < b
• 单侧区间:让区间朝一个方向尽可能的远 a..., a 到无限大

 

// 区间类型
let rang1: ClosedRange<Int> = 1...3
let rang2: Range<Int> = 1..<3
let rang3: PartialRangeThrough<Int> =