// for-in 遍歷String
for c in str.characters{
  print(c)
}
//c是Character類型

// Character和String的相互轉(zhuǎn)換
//let mark = "!" //此時mark是String類型
let mark: Character = "!" //Character必須要顯示聲明
//str + mark //類型不同拼接會報錯
str + String(mark) //進行類型轉(zhuǎn)換后再拼接

// append 相當于 +=
str.append(mark)
//var類型才可以調(diào)用append方法，let類型不可以

// Characters是基于Unicode的
let englishLetter: Character = "a"
let chineseLetter: Character = "哈"
let dog: Character = "��"
let coolGuy = "\u{1F60E}"

// String對Unicode的支持
var coolLetters = "abc" //abc
coolLetters.characters.count //3

var chineseLetters = "你好嗎" //你好嗎
chineseLetters.characters.count //3

var coolGuys = "\u{1F60E}\u{1F60E}\u{1F60E}" //������
coolGuys.characters.count //3

var cafe = "café" //café
var cafe2 = "cafe\u{0301}" //café
cafe.characters.count //4
cafe2.characters.count //4


// String的比較
cafe == cafe2