/*
subscripts(下标): 访问对象中数据的快捷方式
所谓下标脚本语法就是能够通过, 实例[索引值]来访问实例中的数据
类似于以前我们访问数字和字典, 其实Swift中的数组和字典就是一个结构体
Array: subscript (index: Int) -> T
Dictionary: subscript (key: Key) -> Value?
arr[0] == arr.subscript(0)
dict["key"] == dict.subscript("key")
*/
struct Student {
var name: String = "HaRi"
var math: Double = 98.0
var chinese: Double = 99.0
var english: Double = 100.0
func score(course: String) -> Double
{
switch course {
case "math":
return math
case "chinese":
return chinese
case "english":
return english
default:
return math + chinese + english // 此处待探究为何返回nil就会爆红
}
}
//1.要想实现下标访问, 必须实现subscript方法;
//2.要想通过下标访问, 必须实现get方法;
//3.要想通过下标赋值, 必须实现set方法.
subscript(course: String) -> Double?{
get{
switch course {
case "math":
return math
case "chinese":
return chinese
case "english":
return english
default:
return math + chinese + english
}
}
set{
switch course{
case "math":
//以为返回的是可选类型
math = newValue!
case "chinese":
chinese = newValue!
case "english":
english = newValue!
default:
print("not found")
}
}
}
}
var stu = Student(name: "han", math: 99.0, chinese: 98.0, english: 57.0)
print(stu.score(course: "english"))
stu["math"] = 100.0
print(stu["math"]!)
/** Swift中是允许多索引的下标的 **/
struct Mul {
subscript(a: Int, b: Int) -> Int
{
return a + b
}
}
var m = Mul()
print(m[10,20])