swift3.0(学习笔记) 字符串\数组\字典

字符串

let str = "1234"

let wirth = 5678

let strwidth = str + String(wirth)

let strwidth1 = "我又\(strwidth)xxx"

数组

var array = ["a","b","c"]

array.first  //第一个元素 

array.last  //最后一个元素

array.contains("9")  //是否存在该元素

array.contains(3)

let bool1 = arr1 == arr2  //两数组是否相等

array += array //增

array.append ("增")

array.insert("c", at: 2) //插入 位置

array[0] = "aaa"  //替换

array.remove(at: 1) //删除

print(array)

 let emptyArr = [String]()  //空数组

emptyArr1 =[]  //空数组  

//遍历数组

for item in array {

}

字典

var dic = ["A":"a",

                "B":"b",

                ]

for key in dic.keys {

 print(key)

 }

for (key,value) in dic {

 print("key:\(key) -- value:\(value)")

 }

dic["A"] = "Aaaa"

print(dic)

let emptyDic = [String:Float]() //空字典

emptyDic1 =[:]