Operator() 作为下标 (C++)

发布于 2024-08-26 20:52:02 字数 480 浏览 13 评论 0原文

我这样使用operator()作为下标运算符：

double CVector::operator() (int i) const
{
 if (i >= 0 && i < this->size)
  return this->data[i];
 else
  return 0;
}

double& CVector::operator() (int i)
{
 return (this->data[i]);
}

当我获取值时它可以工作，但是当我尝试使用

a(i) = 1;

UPD编写分配值时出现错误：错误文本：

0x651cf54a 处未处理的异常 CG.exe 中的（msvcr100d.dll）：0xC0000005：访问违规读取位置 0xccccccc0。

原文

I use operator() as a subscript operator this way:

double CVector::operator() (int i) const
{
 if (i >= 0 && i < this->size)
  return this->data[i];
 else
  return 0;
}

double& CVector::operator() (int i)
{
 return (this->data[i]);
}

It works when I get values, but I get an error when I try to write assign a value using

a(i) = 1;

UPD: Error text:

Unhandled exception at 0x651cf54a
(msvcr100d.dll) in CG.exe: 0xC0000005:
Access violation reading location
0xccccccc0.

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时光倒影 2024-09-02 20:52:05

正如我在评论中所说，问题在于你的设计有缺陷。我对以下两件事之一做出 100% 的保证：

您传递给赋值函数的值超出了有效范围。
成员data指向内存中的无效空间。

无论哪种情况，我建议添加：

#include <cassert>

并添加 assert(i >= 0 && i < this->size) 而不是静默失败：

double CVector::operator() (int i) const
{
    assert(i >= 0 && i < this->size);
    return this->data[i];
}

double& CVector::operator() (int i)
{
    assert(i >= 0 && i < this->size);
    return (this->data[i]);
}

Like I said in my comment, the problem is your flawed design. I make a 100% guarantee on one of two things:

The value you are passing to the assignment function is out of valid range.
The member data is pointing to invalid space in memory.

In either case, I would suggest adding:

#include <cassert>

and adding assert(i >= 0 && i < this->size) instead of the silent failures:

double CVector::operator() (int i) const
{
    assert(i >= 0 && i < this->size);
    return this->data[i];
}

double& CVector::operator() (int i)
{
    assert(i >= 0 && i < this->size);
    return (this->data[i]);
}

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避讳 2024-09-02 20:52:05

那是因为您还没有在 double& 中实现错误处理。 CVector::operator() (int i) 就像您对另一个重载 () 的函数所做的那样。

将其更改为：

double& CVector::operator() (int i)
{
 if (i >= 0 && i < this->size)
 {
  return this->data[i];
 }
 else // Whatever manner you want to gracefully exit the program
 {
  std::cout<<"Out of bounds!"<<endl;
  exit(1);
 }
}

您还应该考虑将其他函数中的错误处理机制从 return 0; 更改为更有意义的内容。

That's because you haven't implemented error handling in double& CVector::operator() (int i) like you did for the other function which overloads ().

Change it to:

double& CVector::operator() (int i)
{
 if (i >= 0 && i < this->size)
 {
  return this->data[i];
 }
 else // Whatever manner you want to gracefully exit the program
 {
  std::cout<<"Out of bounds!"<<endl;
  exit(1);
 }
}

You should also consider changing the error handling mechanism in the other function from return 0; to something more meaningful.

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