функция друг, перегрузка <<

class Time
    {
    private:
        int hours;
        int minutes;
    public:
        Time();
        Time(int h, int m = 0);
        ...
        friend std::ostream &operator<<(std::ostream &os, const Time &t);
    };

std::ostream &operator<<(std::ostream &os, const Time &t)
{
    os << t.hours << " hours, " << t.minutes << " minutes" << std::endl;
}

cout << Time(12, 0);

cout << Time(12, 0);

Time(12, 0) << cout;

cout << Time(12, 0);

std::ostream &operator<<(std::ostream &os, const Time &t)
{
    os << t.hours << " hours, " << t.minutes << " minutes" << std::endl;
}

cout << Time(12, 0) << Time(15, 1);

std::ostream &operator<<(std::ostream &os, const Time &t)
{
    os << t.hours << " hours, " << t.minutes << " minutes" << std::endl;
    return os;
}

Time(12, 0) << cout;

#include <iostream>
using namespace std;
 
class Time
 {
    private:
        int hours;
        int minutes;
    public:
        Time() : hours(0), minutes(0)
        {}
        Time(int h, int m) : hours(h), minutes(m)
        {}
 
       ostream &operator<<(ostream &os)
       {
            os << hours << ' ' << minutes << endl;
            return os;
       }
};
 
int main()
{
   
   Time(3, 34) << cout;
   
   system("pause");
   return 0;
}

#include <iostream>
 
class A{
};
 
std::ostream & operator<<(std::ostream & lhs,const A & rhs){
   lhs<<"operator<<(ostream,A)"<<std::endl;
   return lhs;
}
 
 
std::ostream & operator<<(const A & lhs,std::ostream & rhs){
   rhs<<"operator<<(A,ostream)"<<std::endl;
   return rhs;
}
 
int main(){
   A()<<std::cout;
   std::cout<<A();
}

Time(3, 34) << Time(69, 35) << cout;

Time(3, 34) << cout;

Time (1, 12) << (Time(3, 34) << cout);

ostream &operator<<(ostream &os)
{
    os << hours << ' ' << minutes << endl;
    return os;
}

Time (1, 12) << (Time(3, 34) << cout);

Time(3, 34) << Time(15, 35) << cout;

#include <iostream>
using namespace std;
 
class Time
 {
    private:
        int hours;
        int minutes;
    public:
        Time() : hours(0), minutes(0)
        {}
        Time(int h, int m) : hours(h), minutes(m)
        {}
 
       ostream &operator<<(ostream &os)
       {
            os << hours << ' ' << minutes << endl;
            return os;
       }
};
 
int main()
{
   
   Time (1, 12) << (Time(3, 34) << cout);
   
   system("pause");
   return 0;
}

cout << что то <<  еще что то << может быть еще что то;

Time(12, 0) << cout;