带下标运算符的重载赋值运算符 [英] overloading assignment operator With subscript operator

问题描述

我重载了下标运算符和赋值运算符，我正在尝试为赋值运算符获取正确的值例子数组 x;x[0]=5;通过重载下标运算符，我可以获得值 0，但是当我重载赋值运算符时，它会进行赋值，但它不使用我的重载函数，因为变量 2 应该具有值 5.

I overloaded both subscript operator and assignment operator and I am trying to get right value to assignment operator example Array x; x[0]=5; by overloading subscript operator i can get value 0 but when i overload assignment operator it does the assignment but it doesn't use my overloaded function because vaiable 2 should have value 5.

class Array
{

public:
    int *ptr;
    int one,two;
    Array(int arr[])
    {
        ptr=arr;
    }

    int &operator[](int index)
    {
        one=index;
        return ptr[index];
    }
    int & operator=(int x){
        two=x;
        return x;
    }   
};

int main(void)
{
    int y[]={1,2,3,4};
    Array x(y);
    x[1]=5;
    cout<<x[0]<<endl;
}

推荐答案

它不使用你的 operator= 因为你没有分配给 Array 的实例，你'正在分配给 int.这将调用您的操作员:

It does not use your operator= because you are not assigning to an instance of Array, you're assigning to an int. This would invoke your operator:

Array x;
x = 7;

如果您想拦截对 operator[] 返回的赋值，您必须让它返回一个代理对象并为该代理定义赋值运算符.示例:

If you want to intercept assignments to what operator[] returns, you must have it return a proxy object and define the assignment operator for that proxy. Example:

class Array
{
  class Proxy
  {
    Array &a;
    int idx;
  public:
     Proxy(Array &a, int idx) : a(a), idx(idx) {}
     int& operator= (int x) { a.two = x; a.ptr[idx] = x; return a.ptr[idx]; }
  };

  Proxy operator[] (int index) { return Proxy(*this, index); }
};

这篇关于带下标运算符的重载赋值运算符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！