object goes out of scope before = operation

manpreet Best Answer 2 years ago

I have thous objects:

Polygon p1, p2;

And I have an inheriting class of Polygon called Triangle, and I try to do:

p1 = Triangle(temp1, temp2, temp3); // temp 1,2,3 are lengths of sides

But for some reason the destructor for Triangle is called at the end of construction.

Rectangle::~Rectangle(void)
{
    Polygon::~Polygon();
}

Polygon::~Polygon(void)
{
    if (sides != NULL)
    {
        delete [] sides;
        sides = NULL;
    }
}

Then it runs the destructor for Polygon a second time.

so after the code ends this is what the debugger says about p1( n is number of sides):

p1  {n=3 sides=0x0062c070 {-17891602} } Polygon

Questions:

• Why does it call the destructor?
• Why both Triangle and Polygon's destructor are called?
• How can this be fixed?

EDIT: as requested:

/*returns true if for the polygons A and B:
(a) for each side on polygon A there is an equal side on polygon B
(b) the number of sides in polygons A and B are equal
(c) sum of sides of A equals the sum of sides of B */
bool Polygon::operator==(const Polygon& p) const
{
    if (n != p.n)
        return false;
    if(circumference() != p.circumference())
        return false;
    for (int i=0; i < n; i++)
        if (!doesSideHasEqual(sides[i], p, n))
            return false;
    return true;
}

Also, thanks for the explanation why it ran ~Polygon, will take into account.

manpreet 2 years ago

Polygon p1;

p1 = Triangle(temp1, temp2, temp3); // temp 1,2,3 are lengths of sides

Polygon& p1;
Triangle t(temp1, temp2, temp3);

p1 = t;

Polygon* p1 = new Triangle(temp1, temp2, temp3);

p1 = Triangle(temp1, temp2, temp3);

Rectangle::~Rectangle(void)
{
    Polygon::~Polygon();  // can be removed
}