swift运算符重载

class Complex {    var real = 0    var virtual = 0    init(real: Int,virtual: Int) {        self.real = real;        self.virtual = virtual    }    func show() -> Void {        if real != 0 {            if virtual > 0 {                print("\(real)+\(virtual)i")            }else if virtual < 0 {                print("\(real)\(virtual)i")            }else {                print(real)            }        }else {            if virtual != 0 {                print("\(virtual)i")            }else {                print("0")            }        }    }    func add(_ other:Complex) -> Complex {    //加法实现        let sum = Complex(real : self.real + other.real,virtual : self.virtual + other.virtual)        return sum    }    //重载运算符    static func ==(left:Complex,right:Complex) -> Bool {        if left.real == right.real && left.virtual == right.virtual {            return true        }        return false    }    static func + (left:Complex,right:Complex) -> Complex {        let res = Complex(real:left.real + right.real,virtual:left.virtual + right.virtual)        return res    }    static func - (left:Complex,right:Complex) -> Complex {        let res = Complex(real:left.real - right.real,virtual:left.virtual - right.virtual)        return res    }    static func * (left:Complex,right:Complex) -> Complex {        let realNum = left.real * right.real - left.virtual * right.virtual        let virtualNum = left.real * right.virtual + left.virtual * right.real         let res = Complex(real:realNum,virtual:virtualNum)        return res    }}var com1 = Complex(real: 3, virtual: 4)com1.show()var com2 = Complex(real: -3, virtual: -4)com2.show()var com3 = com2.add(com1)com3.show()var com4 = com1 + com2com4.show()var com5 = com1 - com2com5.show()var com6 = com1 * com2com6.show()extension Int {    static prefix func ++(num:inout Int) -> Int {        num += 1        return num    }    static postfix func ++(num:inout Int) -> Int {        let temp = num        num += 1        return temp    }    static prefix func --(num:inout Int) -> Int {        num -= 1        return num    }    static postfix func --(num:inout Int) -> Int {        let temp = num        num -= 1        return temp    }}var num = 100var res = ++numprint(num,res)res = --numprint(num,res)var a = 100//var b = a++//print(a,b)var b = a--print(a,b)var s1 = "china"var s2 = "beijing"if s1 == s2 {    print("s1 == s2")} else {    print("s1 != s2")}var arr1 = ["s","d"];var arr2 = ["d","d"];if arr1 == arr2 {    print("arr1 == arr2")} else {    print("arr1 != arr2")}var test1 = Complex(real: 3, virtual: 4)var test2 = Complex(real: 3, virtual: 4)test1.show()test2.show()if test1 === test2 {    print("test1 === test2")} else {    print("test1 !== test2")}if test1 == test2 {    print("test1 == test2")} else {    print("test1 != test2")}