Swift 基本常量和变量,基本数据类型

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//: Playground - noun: a place where people can play

import UIKit

var str = "Hello, playground"

//常量 let

let maxNum = 1000

//maxNum = 2000

//变量 var

var index = 2

index = 3

var x = 1, y = 2, z = 3

//Type inference

//x = "Hello"

var s = "Hello"

let webSite: String = "www.imcooc.com"

//整型

var imIntt: Int = 80

Int.max

Int.min

var imUInt: UInt = 50

UInt.max

UInt.min

UInt8.max

UInt8.min

UInt32.max

UInt32.min

Int64.max

Int64.min

//浮点数

let imFloat:Float = 3.1415927

let imDouble:Double = 3.1415926

var a = 1.25e10

var b = 1.25e-8

//不同类型转换

let x: UInt16 = 100

let y: UInt8 = 20

//x+y//swif不能自动转换类型

let m = x + UInt16(y)//必须类型强制转换

let a:Double = 3.0

let b:Float = 0.3

a + Double(b)

Float(a) + b

let w: Float = 3

let v:Int = Int(3.2)

let integer = 3

let fraction = 0.1415926

let pi = Double(integer) + fraction

let red:CGFloat = 0.2

let green:CGFloat = 0.5

let blue:CGFloat = 0.5

UIColor(red: red, green: green, blue: blue, alpha: 1)

let imTure: Bool = true

let imFalse = false

if imTure {

print("I'm True")

} else if 3 + 4 == 7 {

print("3 + 4 == 7")

}

else {//会出现警告，代码冗余（不会被执行）

print("I'm False")

}

//if 1 {//不可以这样写，整型和布尔值不能混合使用

// print("True")

//}

let a = 1

if a == 1 {

print("True")

}

元组

var point = (5, 2)

var httpResponse = (404 , "Not Found ")

var point2: (Int , Int , Int) = (10, 5, 2)

var httpResponse2:(Int, String) = (200, "OK")

//元组使用

let (x, y) = point

var (statusCode ,statusMessage) = httpResponse

statusCode

statusMessage

statusCode = 405

point.0

point.1

let point3 = (x:3, y:4)

point3.x

point3.y

let point4: (x:Int, y:Int) = (10,5)

point4.x

point4.y

let loginResult = (true, "liuyubobobo")

let (isloginSuccess, _) = loginResult//获取第一个参数，不需要第二个参数用_代替

if isloginSuccess {

print("Login success !")

}

else {

print("Login failed !")

}

//String 字符类型

//使用双引号

var 名字 = "liuyubobobo"

print("我的名字是" + 名字)

//print 函数

let x = 1, y = 2, z = 3, b = true

print(x, y, z, b)

print(x, y, z, separator: ",")//separator 打印的信息分割符（相当于空格）

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Swift 基本常量和变量,基本数据类型

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