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Swift(1) 基本语法

2024-07-28 11:56:39   219人阅读

【适合对象】有一定编程基础的同学

【情景】边看边练，多练多学，自然成长。

【声明】此文章属于原创作品，未经授权，如非法转载，予以追究法律责任。 原文链接：http://www.cnblogs.com/codeAnimal/p/4041545.html

 

练习笔记：

1.var变量
var str = "Hello, playground"println(str)

　2.if语句

var a = 20if a > 10 {    println("if 语句，判断条件 无括号");}

　3.三元运算符

var sy = a > 80 ? "真":"假"println(sy)

　4.指定数据类型

var a1:Int = 10println(a1)

　5.注释符号

//

　6.数据类型

var inta:Int32 = 12 ; println(inta)var floata:Float32 = 10.0 ; println(floata)

　7.控制流 for-in

let indi = [10,201,30]var teamScore  = 0for score in indi {    if score > 50{        println(score)    }}打印结果：201

   //练习1：特殊字符：//..表示 范围


　　var first = 0
　　for i in 0..3{
　　first += i
　　}
　　println(first)

//练习2：计算出 字典中，数字最大值  结果：456let nums = ["prime":[45,456,1,3],"squ":[12,10,32] ]var largest = 0for(k,n) in nums{    for num in n{        if num > largest{            largest = num        }    }}println(largest)

　8.switch语句 （注意：default,必须有）

let vege = "red peper"var title = "default msg"switch vege{    case "red":        title = "red"    case "red","peper":        title = "2";case let y where y.hasSuffix("peper")://特殊用法        println(y)        title = "3"default:    title = "ssss"   }println(title)

　9.while

var n = 2;while n < 50 {    n = n*3}println(n)

　10.计算字符串的长度 countElements

var s = "lljkjij "var l = countElements(s)println(l)

　11.字符串相等 == 

var str1 = "i am liuqinghua"var str2 = "i am liuqinghua"if str1 == str2 {    println("result > "+"==")}else{    println("result >"+"!=")}

　12.数据类型转换

let num1 = 3let num2 = 0.1212var pi = num1 + Int(num2)println(pi)

打印结果：3

　13. Int? 可选类型

var strint = "123"let convertedNum:Int? = strint.toInt()  //不确定 strint是纯数字，还是字符串println("\(convertedNum) result \(convertedNum!)")// 为可选类型的变量设置nil值，表示没有任何值var serverResponse:Int? = 404serverResponse = nil

　14.元组

//形式1.let httpError = (404,"fail")println(httpError.1)//形式2.let httpError2 = (status:404,descrip:"fail")println(httpError2.status)

　15.数组

var shopList:String[] = ["Egg","Milk"]//追加(append)shopList.append("Flour")println(shopList.count) //数组元素个数//插入(insert)shopList.insert("Maple",atIndex:shopList.count)println(shopList)//删除(removeAtIndex)shopList.removeAtIndex(0)println(shopList)//数组的长度shopList.count//遍历1for item in shopList{    println(item)}//遍历2for (index,value) in enumerate(shopList){    println("Item\(index+1):\(value)")}

打印结果： index,下标（从0开始）

　16.字典

var air:Dictionary<String,String> = ["A":"a","B":"b"]//字典追加air["C"] = "c"println(air)//字典删除元素 removeValueForKeylet isDel = air.removeValueForKey("A")println(isDel) //"a" (被删除的值 )println(air)//字典长度 count属性air.count//字典遍历1for (k,v) in air{    println(k+":" + v)}//字典遍历2：分别遍历keys和valuesfor key in air.keys{    println(key)}for value in air.values{    println(value)}//把键转换成数组let airKey = Array(air.keys)println(airKey)

　17.函数

func sumOf(nums:Int...) -> Int{    var sum = 0    var j = 0    for n in nums{        sum += n        j++    }    return sum/j    }//调用方法var code = sumOf(20,20,20)println(code)

　18.类

class Test{    //声明变量    var num:Int = 0    var name:String       //构造函数    init(name:String){        self.name = name;    }        //自定义方法，返回String    func simple() -> String{            return name;    }}var test = Test(name:"liuqinghua")var name = test.simple()println(name)打印结果：liuqinghua

　　

Swift(1) 基本语法


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