перегрузка операций

#include "Darr.h"
 
Darr::Darr(double* A, int N) {
    n = N;
    r = new double[n];
    for(int i = 0; i < n; i++) r[i] = A[i];
}
 
Darr::Darr(const Darr& B) {
    n = B.n;
    r = new double[n];
    for(int i = 0; i < n; i++) r[i] = B.r[i];
}
 
Darr Darr::operator-() {
    Darr R(*this);
    for(int i = 0; i < n; i++) R.r[i] = -r[i];
    return R;
}
 
Darr& Darr::operator=(const Darr& B) {
    if(this == &B) return *this;
    delete[] r;
    n = B.n;
    r = new double[n];
    for(int i = 0; i < n; i++) r[i] = B.r[i];
    return *this;
}
 
Darr Darr::operator+(const Darr& F) const{
    if(n != F.n) {
        puts("Function Darr::operator+(const Darr&): Illegal operated!");
        exit(0);
    }
    Darr G(F);
    for(int i = 0; i < n; i++) G.r[i] += r[i];
    return G;
}
 
double& Darr::operator[](int k) {
    if(k < 0 || k >= n) {
        puts("Function Darr::operator[](int): Illegal index!");
        exit(0);
    }
    return r[k];
}
 
Darr& Darr::operator>>(FILE* out) {
    fprintf(out, "%d \n", n);
    for(int i = 0; i < n; i++) fprintf(out, "%lf \n", r[i]);
    return *this;
}
 
Darr& Darr::operator<<(FILE* in) {
    if(!r) delete []r;
    fscanf(in, "%d", &n);
    r = new double[n];
    for(int i = 0; i < n; i++) fscanf(in, "%lf", &r[i]);
    return *this;
}
////////////////////////////////////////////////////

#ifndef DARR_H
#define DARR_H
 
#include <cstdlib>
#include <cstdio>
 
class Darr {
private:
    int n;
    double* r;
public:
    Darr() {n = 0; r = 0;}
    Darr(double*, int);
    Darr(const Darr&);
    ~Darr() {if(!r) delete[] r;}
 
    Darr& operator=(const Darr&);
    Darr operator-();
    Darr operator+(const Darr&) const;
    double& operator[] (int);
    Darr& operator>>(FILE*);
    Darr& operator<<(FILE*);
 
    ///friend istream& operator<<(istream&, Darr&);
    ///friend ostream& operator<<(ostream&, const Darr&);
};
 
#endif // DARR_H_INCLUDED
/////////////////////////////

#include<iostream>
#include"Darr.h"
 
using namespace std;
 
int main(){
    FILE* filein = fopen("arr.txt", "r");
    FILE* fileout = fopen("arr1.txt", "w");
    Darr s;
    s << filein;
    s >> stdout >> fileout;
    fclose(filein);
    fclose(fileout);
    cout << "========================================" << endl << endl;
    int a;
    int b;
    cout << "vvedite a and b";
    cin >> a >> b ;
    int c = 0;
 
    c = a + b;
    cout << "a = " << a << endl  << "b = " << b << endl;
    cout << "c = " << a << " + " << b << " = " << c << endl << endl;
    system("pause")
    return 0;
}