Swift 系统学习 02 字符串 元组 给元组分量命名

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/*
* 本节内容:
* 1.Bool
* 2.String/Character

* 3.Tuple(*****)

*/


显示和隐式声明Bool类型
let swiftIsCool: Bool = truelet swiftIsHard = falselet value = 10

哪怕只有一行语句, 必须加大括号
必须只能true/false才作为if条件; 非零值不能作为条件
if value == 10 {    print("I think so.")}if swiftIsHard {    print("I donot agree with u.")}

显示和隐式声明字符串和字符
var stringOne = "hello swift"var stringTwo: String = "hello world"

字符串插值(String Interpolation)
var stringThree = "Merge two string: \(stringOne) and \(stringTwo)"

字符串拼接: "+"
var stringFour: String = "Say hello to "let stringFive = "Jonny"let stringReslut = stringFour + stringFive

+=对于字符串来说, 两个字符串拼接好之后, 再赋值给左边变量
mutable: 可变的; NSMutableArray
stringFour += stringFive

字符串和字符的关系: 打印stringFour的所有字符
for character in stringFour.characters {    // character是一个常量    print("stringFour's character is \(character)")}

字符类型必须显示声明
let oneCharacter: Character = "!"String(oneCharacter) + stringFour
let chineseChar: Character = "周"let emojiOne: Character = "                                             
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