Calculating distance between to points of a triangle using pointers - c++

Question

I'm writing a program, where you input triangle point coordinates, the program checks if the triangle exists and outputs the area of the triangle. I have to use pointers in the program.
class Vertex
{
private:
int x, y;
public:
Vertex(int x, int y) : x(x), y(y) {}
int getX() {
return x;
}
int getY() {
return y;
}
float getDistance(Vertex *anotherVertex)
{
float dist;
int tempx = 0, tempy = 0;
tempx = anotherVertex->getX();
tempy = anotherVertex->getY();
dist = ((tempx - x) * (tempx - x) + (tempy - y) * (tempy - y));
return dist;
}
void setCoord(int x, int y)
{
this->x = x;
this->y = y;
}
};
class Triangle
{
private:
Vertex *a, *b, *c;
public:
Triangle()
{
a = new Vertex(0, 0);
b = new Vertex(0, 0);
c = new Vertex(0, 0);
}
void Set_coord()
{
int x1, y1, x2, y2, x3, y3;
cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
a->setCoord(x1, y1);
b->setCoord(x2, y2);
c->setCoord(x3, y3);
}
bool existTriangle() {
float ab = a->getDistance(b);
float bc = b->getDistance(c);
float ca = c->getDistance(a);
if (ab + bc > ca && ab + ca > bc && bc + ca > ab) {
return true;
}
else {
return false;
}
}
float getArea() {
float p;
float ab = a->getDistance(b);
float bc = b->getDistance(c);
float ca = c->getDistance(a);
p = (ab + bc + ca) / 2;
return sqrt(p * ((p - ab)*(p - bc)*(p - ca)));
}
};
I'm struggling to make the getDistance function working as I'm inexperienced with using pointers, when debugging i'm getting this error in the getX() function.
Exception thrown: read access violation.
this was 0xDDDDDDDD.
EDIT:
here is my main()
int main() {
int n = 0;
cin >> n;
vector<Triangle*> vertices;
for (int i = 0; i < n; i++) {
Triangle* newVertices = new Triangle();
newVertices->Set_coord();
vertices.push_back(newVertices);
delete newVertices;
}
for (int i = 0; i < n; i++)
{
if (vertices[i]->existTriangle())
{
cout << vertices[i]->getArea();
}
}
}

Answer 1

The problem is in your main function ( that's why I asked you to post it:) ):
Triangle* newVertices = new Triangle();
vertices.push_back(newVertices);
delete newVertices;
You dynamically allocate memory, that is pointed to by newVertices.
You store the pointer into the vector.
You delete the memory pointed by newVertices.
As a result, now that pointer is a dangling pointer.
So, you must not delete newVertices into the loop.
Do your thing (computer areas, check it a triangle exists, etc.), and then, when you are done, start deleting your dynamically allocating memory...