import Foundation println("Hello, World!") /* int a; */ var a = 10 //隐式类型转换 a = 9 println(a) let b = 10 println(b) /* 类型标注 */ //var x:Int //x = 10.3不支持隐式转换 let x: Int = 10 /* 名称不用在符合标示符的规范 */ let 常量 = 10 /* 基本数据类型:整数类型,小树类书 Int8/16/32/64 UInt8/16/32/64 */ let interger : Int = 10 let unsignedInt:UInt32 = 19 //let overValue:UInt8 = UInt8.max /* 两种基本类型可不可以进行隐式转换 */ var intVar:Int = 10 /* 类型推断和类型安全 */ let stringValue = "hello" var uint8value : UInt8 = 9 var uint16Value : UInt16 = 9 var uint32Value :UInt32 = UInt32(uint8value)+UInt32(uint16Value)//类型转换 /* 类型转换,(类型)表达式 */ //let floatValue:Double = 1231323 var floatValue:Double = 1231323 intVar = Int(floatValue) println(intVar) floatValue = Double(intVar) /* 布尔类型 */ let turnOffLight = 1 if turnOffLight==1 { println("Turn OFF") } else { println("Turn ON") } /* 元组:(30,“hello”) */ let student:(String,Int,Double) = ("zhangsan",23,98.5) println(student.0) println(student.1) println(student.2) let(name,age,_) = student println(name) println(age) //println(score) let student1 = (name:"zhangsan",age:23) println(student1.name) println(student1.age) /* 可选值:optionals,两种状态:有值,没有值 */ var optValue: Int? = nil if (optValue != nil){ println(optValue) } //表示对可选值的一个强制解析,可选值! //var svalue:Int = optValue! //可选绑定 if var svalue = optValue{ println(svalue) } /* 隐式解析可选类型,两种状态,有值,没有纸nil */ var imOptValue:Int! = 8 if (imOptValue != nil){ println(imOptValue) } if let ivalue = imOptValue { println(ivalue) } var ivalue:Int = imOptValue