Swift(1) 基本语法
【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 = 20 if 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 = 10 println(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 = 0 for 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:456 let nums = ["prime":[45,456,1,3],"squ":[12,10,32] ] var largest = 0 for(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 = 3 let num2 = 0.1212 var 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? = 404 serverResponse = 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1 for item in shopList { println(item) } //遍历2 for (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 removeValueForKey let 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1 for (k,v) in air { println(k+":" + v) } //字典遍历2:分别遍历keys和values for 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