what is wrong with my cross product code - c++

Question

I am a C++ beginner. I would like to get the normal vector of a surface, which is determined by three point a,b and c. I have the following code, but I do not know what is wrong with it. Thanks for the help.
#include <iostream>
using namespace std;
class point
{
public:
double x,y,z;
};
class crproduct:point
{
public:
double x1,x2,x3,y1,y2,y3,z1,z2,z3,Ax,Ay,Az,Bx,By,Bz;
point crproduc(point *a,point *b,point *c)
{
//point a
x1 = (*a).x;
y1 = (*a).y;
z1 = (*a).z;
//point b
x2 = (*b).x;
y2 = (*b).y;
z2 = (*b).z;
//point c
x3 = (*c).x;
y3 = (*c).y;
z3 = (*c).z;
//Vector A
Ax = x1-x2;
Ay = y1-y2;
Az = z1-z2;
//vector B
Bx = x2-x3;
By = y2-y3;
Bz = z2-z3;
//cross product
point vector;
vector.x = (Ay*Bz)-(By*Az);
vector.y = -(Ax*Bz)+(Bx*Az);
vector.z = (Ax*By)-(Ay*Bx);
return vector;
}
};
int main ()
{
point *pp, *p1, *p2;
point cd;
crproduct cr1,cr2,cr3,cr4;
(*pp).x = 12;
(*pp).y = 13;
(*pp).z = 15
(*p1).x = 10;
(*p1).y = 10;
(*p1).z = 10;
(*p2).x = 8;
(*p2).y = 5;
(*p2).z = 2;
cd = cr1.crproduc(pp,p1,p2);
cout << cd.x << " " << cd.y << " " << cd.z << endl;
system("pause");
return 0;
}

Answer 1

This is incorrect:
point *pp,*p1,*p2;
point cd;
crproduct cr1,cr2,cr3,cr4;
(*pp).x=12;
(*pp).y=13;
(*pp).z=15
(*p1).x=10;
(*p1).y=10;
(*p1).z=10;
(*p2).x=8;
(*p2).y=5;
(*p2).z=2;
Apart from the missing semicolon, the point *pp,*p1,*p2 line establishes three typed pointers. It doesn't create any objects or instantiate the pointers. So at that point, using the pointers will have undefined results.
You then go on to access the pointers.
If you want them on the stack, just declare the objects directly as:
point pp, p1, p2;
... and then access appropriately. If you need them on the heap then you should use new to create objects that the pointers can point to, e.g.
pp = new point;
And don't forget to delete later.