05-Swift 数组的使用

一、数组的定义

//不可变数组
let a = [1,2,3]

//可变数组
var b:[Any] = ["a","b","c"]
b[1] = 3
b   //["a", 3, "c"]

//  Array<Any> 等效于 [Any]
var c:Array<Any> = [1,2,3,4,"a"]
c[1] = "d"
c   //[1, "d", 3, 4, "a"]

var aaa = [String]()
aaa.append("a")
aaa.append("ccc")
aaa  //["a","cc"]

二、数组的基本操作

• 增加元素

// append
var aa = [2,1,3,5]
aa.append(4)
aa  //[2, 1, 3, 5, 4]

// insert
aa.insert(6, at: 2)
aa  //[2, 1, 6, 3, 5, 4]

• 删除元素

aa.remove(at: 1)
aa  //[2, 6, 3, 5, 4]

aa.popLast()    //弹出最后一个元素
aa  //[2, 6, 3, 5]

aa.removeLast()
aa  //[2, 6, 3]

//删除最后两个元素
aa.removeLast(2)
aa  //[2]

• 改元素

aa[0] = 3
aa  //[3]

• 查元素

var bb = ["a","b","c","d","e","f","g"]
bb[4]   //"e"
bb[1...4]   //["b", "c", "d", "e"]

bb.max()    //"g"
bb.min()    //"a"

三、数组的其它操作

var cc = ["aa","bb","cc","dd"]

• 求个数

//个数
cc.count    //4
//容量
cc.capacity    //容量：4

cc.append("ee")
cc.count    //5
cc.capacity    //容量：8  (容量以原有容量的两倍增加)
cc    //["aa","bb","cc","dd","ee"]

• 遍历

for i in 0..<cc.count{
    print(i)    //五次
}

for value in cc {
    print(value)
}

//设置遍历区间
for value in cc[2...4]{
    print(value)    //cc/dd/ee
}

//遍历时取出下标
for (key,value) in cc.enumerated(){
    print(key,value)
}

• 数组的合并

//要合并的数组类型必须一致
let dd1 = [1,2,3]
let dd2 = [2,3,4,5]
dd1 + dd2   //[1, 2, 3, 2, 3, 4, 5]

let ee1 = ["aa","bb","cc"]
let ee2 = ["cc","bb"]
ee1 + ee2   //["aa", "bb", "cc", "cc", "bb"]

let ff1:[Any] = [1,2,"f1"]
let ff2:Array<Any> = [4,32,"f2"]
ff1 + ff2   //[1, 2, "f1", 4, 32, "f2"]