Swift初级:变量与数据类型
发布时间:2020-12-14 01:50:48 所属栏目:百科 来源:网络整理
导读://: Playground - noun: a place where people can playimport UIKit//1.第一个程序var str = "Hello,playground"println("Hello,swift!")//2.let 常量constants, var 变量variableslet webSiteName:String = "www.baidu.com"var 整型:Int = 10let bignum_a
//: Playground - noun: a place where people can play import UIKit //1.第一个程序 var str = "Hello,playground" println("Hello,swift!") //2.let 常量constants, var 变量variables let webSiteName:String = "www.baidu.com" var 整型:Int = 10 let bignum_a = 1000000 let bignum_b = 1_000_000 let bignum_c = 1_0000_0000 var 浮点型64:Double = 10.0,浮点型32:Float = 10.0 var red,green,blue:Double //强制类型转换 let integer_a:Int = 3 let double_b:Double = 0.1415926 let pi = Double(integer_a) + double_b //3.布尔类型以及if语句 let imtureVar:Bool = true let imfalseVar:Bool = false if imtureVar { println(imtureVar); }else{ println(imfalseVar); } //4.Tuples 元组 let registerResult = (isRegisterSuccess:true,nickname:"慕课女神",gender:"女") //遍历元组1 let (isRegisterSuccess,nickname,gender) = registerResult isRegisterSuccess nickname gender //遍历元组2 registerResult.0 registerResult.1 registerResult.2 //遍历元组3 registerResult.isRegisterSuccess registerResult.nickname registerResult.gender //使用下划线(_)忽略部分数值 let connectionResult : (Bool,Int,String) = (true,404,"Not Found") let (isLoginSuccess,_,_) = connectionResult if(isLoginSuccess){ println("登录失败!!!") } //5.可选型Optionals:或者是一个值,或者是没有值nil var a:Int? a = 12 let userInput = "18" var age = userInput.toInt() if(age != nil){ println("your age is (age)"); println("your age is (age!)");//一定是有值的,安全的,即可选型的解包 println("your age is " + String(age!)); }else{ println("Invalidate userInput"); } //Optional Binding if let userAge = userInput.toInt() { println("your age is (userAge)"); }else{ println("Invalidate userInput"); } //可选型 let strName:String? = "test" strName strName! let strB:String! = "test" strB (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |