Swift函数 - 指针类型

var m = 10
var n = 20
func swapNum(var m:Int, var n:Int){
    let tmp = m
    m = n
    n = tmp
}
swapNum(m, n: n)
print("m=\(m),n=\(n)") //"m=10,n=20\n"

最后m和n的值根本没有交换，这是因为函数默认是值传递

// 指针类型
var m = 10
var n = 20
func swapNum(inout m:Int, inout n:Int){
    let tmp = m
    m = n
    n = tmp
}
swapNum(&m, n: &n)
print("m=\(m),n=\(n)") //"m=20,n=10\n"

注意只需要在参数里写上关键字inout