C++ :: Arithmetic Operators Overloading For Class With Pointer

I am stucked in a problem of overloading arithmetic operators such as "+,*" for a class in the form

class Point {
int N; // dimension of the point
double *Pos; // length of N
}

My assign operator is :
Point& Point::operator= (const Point& pt) {
N= pt.N;
if(Pos == NULL) Pos = new double[N];
memcpy(Pos, pt.Pos, N*sizeof(double));

[Code] ....

The add operator "+" is:
Point operator+( const Point& pt1, const Point& pt2 ) {
Point ptr = Point(pt); // this is a constructor
for (int i=0; i<pt1.N; i++) ptr.Pos[i] += pt2.Pos[i];
return ptr;
}

Based on the above overloading, What I am going to do is :

P = alpha*P1 + beta*P2; // alpha and beta are double constants, P1 and P2 are Points objes

It is ok with Intel C++ 14.0 compiler, but does not work with the microsoft visual c++ 2012 compiler in debug mode in visual studio 2012.

I stepped in those operators and found that visual c++ compiler deconstructs the ptr in operators "*" and "+" before its return while intel c++ finished the operation P = alpha*P1 + beta*P2; and delete those ptrs at last.

Portability of my operator overloading is worse. How to get those arithmetic operators overloading for class with pointers in it.