Question

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.

Answer 1

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

1. The value you are passing to the assignment function is out of valid range.
2. 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]);
}