error: 'VD<Class1> Class2::data' is private within this context - c++

Question

I'm having some problems with my code. I declared in the .h two friend functions which are:
#ifndef CLASS2_H
#define CLASS2_H
#include "class1.h"
#include <string>
#include <iostream>
using namespace std;
class Class2{
private:
VD<Class1> data; //Vector of objects of Class1
VD<int> number; //Vector of int
public:
Constructor();
friend istream & operator >> (istream & i, const Class1 & other);
friend ostream & operator << (ostream &o, const Class1 & other);
};
#endif
And the .cpp is:
istream & operator >> (istream & i,Class2 & other){
string n;
Class1 ing;
getline(i,n);
while(!i.eof()){
i >> ing;
otro.data.Insert(ing,otro.data.size()-1);
}
return i;
}
ostream & operator << (ostream &o, const Ingredientes & otro){
for(int i = 0; i < otro.datos.size(); i++){
o << other.data[i];
}
return o;
}
So, the error that I'm getting is:
error: 'VD Class2::data' is private within this context. I declared the functions of operator >> y << friend but I doesn't make any sense that compiler says to me that I can't access to the private data. Any help please?

Answer 1

You seem to be very new at C++, and you seem to be doing quite complex things, while you're not understanding the basics yet. Please find a tutorial or so.
A few things:
using namespace std; is -especially in a header- never a good idea. It's like you're going on holiday, but bring along everything in your house. Refer to standard namespace functions using std::.
an istream& operator>>() cannot put anything in an object that is declared const.
using vec.insert(obj, vec.size()-1) is reinventing one of the most essential funcitons of std::vector: push_back()...
while (!i.eof()) is not good, because eof is not set until after the read past the end.
there's no string& operator>>(string& str, Class1& obj) function defined. We have std::stringstream for that.
To show how you could realize some of this, I'm going to write some example code. Please don't just copy it, but try to understand it.
test.txt
1 2 3 4
5 6 7 8
main.cpp
#include <vector>
#include <iostream>
#include <string>
#include <sstream>
#include <fstream>
template <typename T>
using VD = std::vector<T>;
class Class1 {
private:
int d;
public:
friend std::istream& operator>> (std::istream& i, Class1& obj) {
i >> obj.d;
return i;
}
friend std::ostream& operator<< (std::ostream& o, const Class1& obj) {
o << obj.d;
return o;
}
};
class Class2 {
private:
VD<Class1> data{}; //Vector of objects of Class1
public:
void Clear() { data.clear(); }
friend std::istream& operator>> (std::istream& i, Class2& obj) {
std::string line;
std::getline(i, line);
std::istringstream iss(line);
Class1 ing;
while (iss >> ing) {
obj.data.push_back(ing);
}
return i;
}
friend std::ostream& operator<< (std::ostream& o, const Class2& obj) {
for (auto const& cl1 : obj.data) {
o << cl1 << " ";
}
return o;
}
};
int main() {
Class2 cl2;
std::ifstream ifs;
ifs.open("test.txt");
if (ifs.is_open()) {
ifs >> cl2;
}
std::cout << "first line: " << cl2 << '\n';
cl2.Clear();
if (ifs.is_open()) {
ifs >> cl2;
}
std::cout << "second line: " << cl2 << '\n';
ifs.close();
}