初探Swift一 - 变量与数据类型
初探Swift,Swift变量声明,let和var分别声明常量和变量。Swift数据类型,包括整型,浮点型,字符型,布尔型,可选型等,已经强制类型转换和if选择。
//-----------变量相关----------
//常量
let maxNum = 1000
//变量
var index = 0
var a=0.0, y=0, z=0
a = 1;
a = 1.1;
//报错
//a = "a";
//显示申明类型
var test : Int
test = 10
var red, green, blue : Int
//十进制
red = 17;
//二进制,以0b开头
red =0b10001
//八进制,以0o开头
red = 0o21
//十六进制,以0x开头
red = 0x11
//科学计数法
let b = 0.012
letc =1.2e-2
//多位整数的表示法
lete =1000000
letf =1_000_000
letg =1_000_000
//自动类型转换
let h:Float = 1
//Xcode beta2会将1.2转为1,而Xcode beta3直接报错。
//let i:Int = 1.2
//强制类型转换
let j:Double = Double(h) + b
//变量名,任何unicode都可以
let 姓名 = "小明"
println(姓名 + ",你好")
//----------选择-----------
let bool1 = true
let bool2:Bool = false
//即使语句块只有一行,花括号{}也不能省略,在选择里,只有true和false,1和0都是不可以的。
if bool1{
println("hello");
}else if bool2{
println("world");
}else{
println("swift");
}
//---------元组-----------
let tuples_1 = ("小明", "男", 21, true)
//元组可以赋值给变量
let (name, sex, age, status) = tuples_1
println("姓名:"+name+",性别:"+sex);
//元祖可以用.0,.1,.2来访问
println("姓名:"+tuples_1.0+",性别:"+tuples_1.1);
//每个元祖都赋一个key
let tuples_2 = (date:"2015-01-05", time:"16:06", author:"lane")
println("日期:"+tuples_2.date+" "+tuples_2.time+",作者:"+tuples_2.author);
println("日期:"+tuples_2.0+" "+tuples_2.1+",作者:"+tuples_2.2);
//至提取元组的第一个值,不关心后面的值
let login = (true, "小明")
let (staic, _) = login
if staic{
println("hi");
}else{
println("hi hi");
}
//元组的类型显示声明
let login2:(Bool, String) = (true, "小明")
//可选型optional
var optionalVar1:Int?
optionalVar1=1
let userAge = "18"
var age = userAge.toInt()
if(age != nil){
println("You age is " + String(age!) )
}else{
println("Invalidate userInput")
}
//解包
if let userInput = userAge.toInt(){
println("you age is\(userInput)");
}
let m:String? = "hello";
let n:String! = "hi";
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