Swift

1，if语句

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if count >=3 {     println("yes") }else{     println("no") }

2，switch语句 

（1）Swift中不需要在case块中显示地使用break跳出switch。如果想要实现C风格的落入特性，可以给需要的case分支插入fallthrough语句

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var fruit = "apple" switch fruit{     case "apple":         println("good")         fallthrough     case "banana","orange":         println("great")     default:         println("bad") }

（2）case分支还可以进行区间匹配

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var age = 5 switch age {     case 0...11:         println("正太")     case 12...30:         println("少年")     default:         println("大叔") }

（3）使用元组匹配（判断属于哪个象限）

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let point = (2,2) switch point {     case (0,0):         println("坐标在原点")     case (_,0):         println("坐标在x轴上")     case (0,_):         println("坐标在y轴上")     case (-3...3, -3...3):         println("坐标在长宽为6的正方形内")     default:         println("在什么地方") }

（4）case中还可以使用where关键字来做额外的判断条件

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var height = 1.72 switch height{     case 1...3 where height == 1.72:         println("case 1")     case 1...3 where height == 2:         println("case 2")     default:         println("default") }

3，for循环语句 

（1）for条件递增循环

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for var i=1; i<100; i++ {     println("(i)") }

（2）for-in循环

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for i in 1..<100{     println("(i)") }   //遍历数组元素 let numbers = [1,2,4,7] for num in numbers{     println("(num)") }   //遍历字典 let nameOfAge = ["lily":18, "Candy":24] for (aName, iAge) in nameOfAge{     println("(aName) is (iAge)") }   //遍历字符串的字符 for chare in "hangge" {     println(chare) }

4，while循环语句

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while i<100 {     i++ }   do{     i++ }while i<100