运算符重载

操作的对象不同，意义不同

数学运算

let a = 1 
let b = 2 
let c=a+b

字符串拼接

let fn = "张" 
let ln = "三" 
let nn = fn+ln

数组拼接

let arr1 = ["a","b"] 
let arr2 = ["c","d"] 
let arr3 = arr1 + arr2

复合运算符

就是将两个运算符合在一起使用

var ss = 90

ss-=10


var quote = "一二三四五"

quote += "六七八九十"

switch

穿透 fallthrough

let today = days.tue

switch today {

case days.sun:

    print("周日")

case .monday:

    print("周一")

case .tue:

    print("周二")

    fallthrough

case .wen:

    print("周三")

case .thue:

    print("周四")

**case** .fri:

    print("周五")

case .sta:

    print("周六")

}

范围运算符

半开区间,不包含右侧5

for i in 0..<5{

    print(i)

}

闭区间，包括右侧

for j in 0...5{

    print(j)

}