var dict1 = ["swift":"張三","python":"李四","java":"老王"]
print(dict1)
print(dict1.count)
print(dict1.isEmpty)
print(dict1["swift"]!)

//空字典的定義
var empty1:[Int:String] = [:]
var empty2:Dictionary<String,String> = [:]
var empty3 = String:String

//字典的特點(diǎn):1)無(wú)序 2)鍵不能重復(fù)
let a = [1:"a",2:"b",3:"c"]
let b = [3:"c",2:"b",1:"a"]
print(a==b)//true

//遍歷
for key in dict1.keys{
print(key)
}
for value in dict1.values{
print(value)
}
for (key,value) in dict1{
print(key,value)
}

//添加or修改(如果這個(gè)Key當(dāng)前沒(méi)有，添加操作；如果當(dāng)前這個(gè)Key存在，修改操作)
var user = ["name":"lw","pwd":"123","job":"student"]
user["name"] = "maotu"
print(user)

//修改
var oldPwd = user.updateValue("456",forKey:"pwd")!//返回原來(lái)value的值
if oldPwd == user["pwd"]{
print("修改后的密碼與修改前一樣，可能會(huì)導(dǎo)致安全問(wèn)題！")
}
print(user)

//添加
user["email"] = "56429@qq.com"
user.updateValue("chuzhou",forKey:"location")
print(user)

//刪除
user.removeValue(forKey:"location")
user["email"] = nil //null
print(user)