Swift_下标

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func testSubscripts() {

    //下标关键字subscript

    //array测试

    struct TestArray {

        //内部数组

        var array = Array<Int>()

        //下标使用

        subscript(index: Int) -> Int {

            get {

                assert(index < array.count, "下标越界")

                return array[index]

            }

            set {

                while array.count <= index {

                    array.append(0)

                }

                array[index] = newValue

            }

        }

    }

    var array = TestArray()

    array[3] = 4; //通过下标设置值

    print(array)

    print("\(array[3])") //4

    print("\(array[4])") //程序停止

}