import Foundation

// let变量不可变
let myName = "Gary"
let yourName = "Foo"

// var变量可以改变
// structur
var names = [
    myName,
    yourName
]

names.append("Mike")

// 值拷贝
let foo = "Foo"
var foo2 = foo
foo2 = "Foo2"
foo

let moreName = [
    "Gary",
    "Mike",
    "Sara"
]

// let -> var
var copy = moreName
copy.append("Foo")
moreName

// class 指针传递，let只保证指针不改变
let oldArray = NSMutableArray(
    array: ["Mike", "Paul"]
)

oldArray.add("Baz")

var newArray = oldArray
newArray.add("Qux")
newArray
oldArray


// 一些函数签名表示不改变变量，实际上改变
let someNames = NSMutableArray(
    array: ["Mike", "Paul"]
)
func changTheArray(_ array: NSArray) {
    let copy_address = array as! NSMutableArray
    copy_address.add("Bazz")
}

changTheArray(someNames)
someNames