如何用下标运算符中分配的值来做一些事情? [英] How to do some stuff with values assigned in subscript operator?

问题描述

假设我将数据数组0,0,1,1,2,2,5,5,7,7,2,2作为类中的数据成员，而我想在此类数组中定义下标运算符

Suppose i've data array 0,0,1,1,2,2,5,5,7,7,2,2 as data member in class and i want to define subscript operator in such they

[i]返回2 * i数组元素，但我也想让用户设置元素，所以

[i] returns me 2*i element of array but also i want let user to set elements, so

[i] = n，必须同时应用于2 * i和2 * i + 1.

[i] = n, must be applied to both 2*i and 2*i+1.

是否可以只向用户显示下标运算符?

Is it possible to do it with showing to user only subscript operator?

0,0,1,1,2,2,5,5,7,7,2,2
[3] = 4;
0,0,1,1,2,2,4,4,7,7,2,2

另一个解决方法?通常，它可能不仅是两个元素.

another workarounds? and in general it may be not only two elements.

推荐答案

间接，是的.

您可以使用下标运算符返回一个专用类型，该运算符的工作原理基本上类似于函子，并会根据您的规范分配值:

You can return a dedicated type with the subscript operator that works basically like a functor and takes care of assigning the value according to your specification:

struct AssignFunctor {
  MyArrayType& parent;
  size_t index;
  AssignFunctor(MyArrayType& parent, size_t index) : parent(parent), index(index) {}
  AssignFunctor& operator=(int k) {
    parent.set(index,k);
    parent.set(index*2,k);
  }
  operator int() const {
    return parent.get(index);
  }
};

struct MyArrayType {
  AssignFunctor operator[](size_t index) {
    return AssignFunctor(*this,index);
  }
  int operator[](size_t index) const {
    return get(index);
  }
  void set(size_t,int);
  int get(size_t) const;
};

这篇关于如何用下标运算符中分配的值来做一些事情?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！