Objektovo orientované vektory v C++

Zdravím,
potreboval by som naprogramovať nejakú funkciu/konštruktor k hlavičkovému súboru vektoris.h (nie moja tvorba) dole aby bolo možné už deklarované a definované vektory re-inicializovať.Je to vôbec možné? Napr.

Vector3D vek(1,2,3); //toto je OK, funguje to cez konštruktory
vek(2,4,3); //toto potrebujem nejak naprogramovať. cieľom je aby hodnoty 1 2 3 v už existujúcom vektore vek boli zmenené na 2 4 3

#ifndef _VECTOR

#define _VECTOR

#include <math.h>



class Vector3D

{

private:

double x, y, z;

public:

//default constructor

Vector3D(double X , double Y , double Z )

{

x = X;

y = Y;

z = Z;

}



~Vector3D(){};



//calculate and return the magnitude of this vector

double GetMagnitude()

{

return sqrtf(x * x + y * y + z * z);

}



//multiply this vector by a scalar

Vector3D operator*(double num) const

{

return Vector3D(x * num, y * num, z * num);

}



//pass in a vector, pass in a scalar, return the product

friend Vector3D operator*(double num, Vector3D const &vec)

{

return Vector3D(vec.x * num, vec.y * num, vec.z * num);

}



//add two vectors

Vector3D operator+(const Vector3D &vec) const

{

return Vector3D(x + vec.x, y + vec.y, z + vec.z);

}



//subtract two vectors

Vector3D operator-(const Vector3D &vec) const

{

return Vector3D(x - vec.x, y - vec.y, z - vec.z);

}



//normalize this vector

void normalizeVector3D()

{

double magnitude = sqrtf(x * x + y * y + z * z);

x /= magnitude;

y /= magnitude;

z /= magnitude;

}



//calculate and return dot product

double dotVector3D(const Vector3D &vec) const

{

return x * vec.x + y * vec.y + z * vec.z;

}



//calculate and return cross product

Vector3D crossVector3D(const Vector3D &vec) const

{

return Vector3D(y * vec.z - z * vec.y,

z * vec.x - x * vec.z,

x * vec.y - y * vec.x);

}



void setX(double);

void setY(double);

void setZ(double);



double getX();

double getY();

double getZ();

};







#endif