Pass array to the derived class in C++ - c++

Question

In Class Dim I created array G and I want to pass it to the derived Class PHYS_FIELD. Instead of output (0..9) it gives (0..0). I realize that it is just a new copy of G but I do not know how to do it correctly.
arr1.h:
#ifndef ARR1_H
#define ARR1_H
#include<iostream>
using namespace std;
template <class T> class arr1
{
public:
T* data;
size_t size;
arr1(const size_t isize)
{ size=isize;
data = new T[size];
}
T & operator ()(size_t const index)
{ return data[index]; }
};
#endif /*ARR1_H */
dim.h:
#ifndef DIM_H
#define DIM_H
#include "arr1.h"
class DIM {
public:
DIM();
protected:
int N;
};
#endif /* DIM_H */
dim.cpp:
#include "arr1.h"
#include "dim.h"
using namespace std;
DIM :: DIM()
{
N=10;
arr1<double> G(N);
for (int i=0; i<N; i++)
G(i)=i;
};
phys_field.h:
#ifndef PHYS_FIELD_H
#define PHYS_FIELD_H
#include "dim.h"
#include "arr1.h"
class PHYS_FIELD : public DIM {
public:
PHYS_FIELD();
arr1<double> G;
};
#endif /* PHYS__FIELD_H */
phys_field.cpp:
#include "dim.h"
#include "phys_field.h"
#include <arr1.h>
using namespace std;
PHYS_FIELD :: PHYS_FIELD(): G(N) {
cout<< " from phys_field.cpp "<<endl;
cout<<N<<endl;
for (int i=0; i<N ; i++)
cout<<i<<" "<<G(i)<<endl;
};
main.cpp:
#include "dim.h"
#include "phys_field.h"
using namespace std;
int main(int argc, char* argv[]){
PHYS_FIELD *F= new PHYS_FIELD();
return 0;
}

Answer 1

modify class arr1 and add a constructor that accepts zero parameters (this way we can declare arr1 G and later build it in DIM::DIM constructor
arr1()
{
}
class DIM:
protected:
arr1<double> G; //I've moved G from the constructor so that PHYS_FIELD can inherit it directly
DIM::DIM()
{
N=10;
G = arr1<double>(N);
for (int i=0; i<N; i++)
G(i)=i;
};
class PHYS_FIELD
remove arr1<double> G; from PHYS_FIELD header so that it doesn't hide the G inherited from DIM
PHYS_FIELD::PHYS_FIELD() { //removed G(N)
cout << " from phys_field.cpp " << endl;
cout << N << endl;
for (int i=0; i<N; i++)
cout << i << " " << G(i) << endl;
};
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