Question

#include <iostream>
#include <fstream>
using namespace std;

class Integer 
{
    public:
    int i;

    Integer (int ll = 0, int k = 0) : i (ll) 
    {
        cout << "\nconstructor A\n";
    }

    Integer operator<< (const Integer& left, const Integer& right);
};

Integer operator<< (const Integer& left, const Integer& right)
{
    cout << "\ndsfdsfdsf : " << "===" <<  right.i << "\n";
    return left ;
}

int main () 
{
    Integer l;

    l << 5 << 3 << 2;

    return 0;
}

This code gives the above titled error when I remove the keyword friend from the declaration of the << operator.
There isn’t anything private here, so why is it happening?

Answer 1

When the operator declaration does not contain friend, the declaration declares a member, and a member has its class as its implicit first argument. With the two explicit arguments, this makes three arguments for a binary operator.