Swift教程之运算符

import Foundation//4、复合赋值操作符var a = 1a += 2//一元减运算符（一个数值前加了符号-，叫作一元减运算符）let three = 3let minusThree = -three //minusThree = -3let plusThree = -minusThree // plusThree = 3//一元加运算符（一元加运算符(+)返回的值，不做任何变动）let minusSix = 6let alsoMinusSix = +minusSix // alsoMinusSix = 6//6、三元条件运算符//特别注意：三目运算符里面的(?)前面一定要有至少一个空格let contentHeight = 40let rowHeight = contentHeight + (contentHeight > 20 ? 50 : 20)//7、范围运算符//封闭范围运算符（包括a和b）for index in 1...5 {    print("\(index) times 5 is \(index * 5)")}//半封闭的区域运算符（包头不包尾）let names = ["Anna", "Alex", "Brian", "Jack"]let count = names.countfor i in 0..<count{    print("Person \(i) is called \(names[i])")}