Day2 (operation)/(optional Value of double eye Value)
Posted Tony0571
tags:
篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了Day2 (operation)/(optional Value of double eye Value)相关的知识,希望对你有一定的参考价值。
let secondSystem:Int = 0b10001
let eightSystem:Int = 0o21
let tenSystem:Int = 17
let sixthSystem:Int = 0x11
// summary: 1.u need insert a "Enter" behind equal symbol
let num_a:Float = 1
let num_b:Int = 1
let a:Int = 3
let b:Double = 0.1415926
let pi:Double = Double(a) + b
// summary: 2.it need change two number‘s type in the same ,in order to getting the result
let bignum_a:Float = 10/2.5
let bignum_a2:Int = 10/3
let bignum_b:Float = Float(Int(1.2))*10.1
let bignum_c:Int = Int(3.99)
// summary: 3.it need change two number‘s type in the same ,in order to getting the result
// 4.forcing number type need add type symbol in the front of number
let jy = "爱下厨"
let address = ".Jianggan,Hangzhou City,ZheJiang Province,China"
jy + address
let params = (isLoginSuccess:true,name:"tommy",age:25)
let (isLoginSuccess,name,age) = params
let isLginSuccess = params.0
let whats = params.name
let whatsage = params.2
let (isTrue,_,_) = params
if (isTrue)
{
print("login success!")
}
let personArray = ("a","b","c","d")
let aPerson = personArray.0
let bPerson = personArray.1
// summary: 5. Tuples
var value_a:Int
value_a = 1
var imOptionalVariable:Int?
// summary: it‘s equal to nil when the optionalVariable is empty
imOptionalVariable = 56
let name = "Tommy"
var age = Int(name)
if age != nil
{
print("it‘s not empty")
}
else {
print("it‘s empty!")
}
let userage = "25"
var currentAge = Int(userage)
let currentnewAge = Int(userage)
// summary: String toInt use method : Int(string)
if currentAge != nil
{
print("age: \(currentAge)")
print("his age is " + String(currentAge!))
}
if userage .isEmpty
{
print("age: \(userage)")
}else {
print("age :\(userage)")
}
let stringA:String? = "optional_String"
let string2 = "_/stringA"
var stringB = stringA! + string2
stringA
stringA!
以上是关于Day2 (operation)/(optional Value of double eye Value)的主要内容,如果未能解决你的问题,请参考以下文章
optiona=false导致的问题之Hibernate源码分析
华为运营商级路由器配置示例 | 配置OptionA方式跨域BGP VPLS示例
华为运营商级路由器配置示例 | 配置OptionA方式跨域LDP VPLS示例