Swift学习：10.运算符

1.基本运算符

1）一元运算符

• 自增自减运算符：++ --
• 正号负号运算符：+ -
• 逻辑非运算符：！

2）二元运算符

• 赋值运算符：a = b
• 算数运算符：+ = * /
• 求余运算符：%
• 符合赋值运算符： += -= *= /=
• 比较运算符： == != > < >= <=
• 空合运算符：?? a ?? b 相当于 a != nil ? a! : b
• 区间运算符：a...b a..<b
• 逻辑与或运算符：&& ||

3）三木运算符

• 问题？答案1：答案2

2.重载运算符

Struct Sword{

var length: Float

var weight:Float

var name :String

}

//重载运算符“+”

func +(left: Sword,right:Sword)->Sword{

return Sword(length : left.length + right.length,

weight : left.weight + right.weight,

name: “Big Sword”)

}

//重载前置运算符“-”

prefix func-(sword:Sword)->Sword{

return Sword(length: -sword.length,

weight: - sword.weight,

name: “Small Sword”)

}

//重载后置运算符“++”

postfix func++(inout Sword)->Sword{

var oldSword = Sword

sword.length += 1.0

sword.weight += 1.0

return oldSword

}

3.自定义运算符

infix operator +-* {associativity left precedence 140}

func +-*(left: Sword,right:Sword)->{

return Sword(length:left.length + right.length,

weight:left.weight + right.weight,

name:left.name + right.name)

}

第一段：operator infix/prefix/postfix自定义运算符{}
第二段：infix/prefix/postfix func (参数表) ->返回类型{}

4.示例代码：

println("Hello,World!")

let name = "sn"

let dog:Character = "a"

let cow:Character = "b"

//let dogCow = dog + cow

let contentHeight = 40

let hasHead = true

let roheight = contentHeight + (hasHead ? 50 : 20)

for index in 1...5

{

println(index)

}

let names = ["a","b","c","d"]

let countNumber = names.count

for index in 0..<countNumber

{

println(names[index])

}

for name in names

{

if name.hasPrefix("c"){

println("1")

}

}

for character in "asfedee"

{

println(character)

}

let heart = "\u{2665}"

println(heart)

let unusualMenagerie = "Koala

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