This should call the assignment operator, but how? - c++

Question

I am a C++ newbie here. My assignment is to create a Vector class without using the Vector class that already exists. I am not sure if I have implemented the assignment operator correctly. If so, how can I use it in the main function?
# include <iostream>
# include <string.h>
using namespace std;
class Vector{
public:
unsigned int * p;
size_t size;
Vector(){ // Default contructor
cout << "The default contructor" << endl;
this -> size = 20; // initial value
this -> p = new unsigned int [size];
// trying to set every elements value to 0.
for(int i = 0; i < size; i++){
*(p+i) = 0;
}
}
Vector (const Vector & v){ // The copy contructor
cout << "The copy constructor" << endl;
this -> size = v.size;
p = new unsigned int[size];
for(int i = 0; i < size; i++){
*(p+i) = *(v.p + i);
}
}
Vector& operator = (const Vector & v){
cout << "The assignment operator" << endl;
this -> size = v.size;
p = new unsigned int[size];
for(int i = 0; i < size; i++){
*(p + i) = *(v.p + i);
}
//p = p - size; // placing back the pointer to the first element
//return *this; // not sure here
}
void print_values(){
for(int i = 0; i< size; i++){
cout << *(p + i) << " ";
}
cout << endl;
}
};
int main(){
Vector * v1 = new Vector();
(*v1).print_values();
Vector * v2; // this should call the assignment operator but......... how?
v2 = v1;
(*v2).print_values();
Vector v3(*v1);
v3.print_values();
}

Answer 1

Your line:
v2 = v1;
Won't call your assignment operator. It just assigns one pointer to another pointer. You need to make an assignment between objects for your operator to be used.
You want something like:
Vector v1;
v1.print_values();
Vector v2;
v2 = v1;
And so on. Your program has some memory leaks, too - watch out!
Editorial note: Why *(p+i) instead of p[i]? The latter is a lot easier to read.

Answer 2

You are assigning one pointer to another, not one class instance to another. In order to invoke your assignment operator, you need to have two class instances (you only have one) and then deference the pointers so you access those instances, eg:
int main(){
Vector * v1 = new Vector();
v1->print_values();
Vector * v2 = new Vector();
*v2 = *v1;
v2->print_values();
Vector v3(*v1);
v3.print_values();
delete v1;
delete v2;
}
Alternatively:
int main(){
Vector v1;
v1.print_values();
Vector v2;
v2 = v1;
v2.print_values();
Vector v3(v1);
v3.print_values();
}