Overloading << operator for std::ostream

Question

ostream& operator <<(ostream& osObject, const storageRentals& rentals)
{
    osObject << rentals.summaryReport();
    return osObject;
}

summaryReport() is a void function, and it is giving me an error:

no operator "<<" matches these operands

but the error is not there if I change the summaryReport function to an int, but the problem I have with that is you have to return a value, and it is printing it out on the screen.

void storageRentals::summaryReport() const
{
   for (int count = 0; count < 8; count++)
      cout << "Unit: " << count + 1 << "    " << stoUnits[count] << endl;
}

Is there any way to overload cout << with a void function?

Answer 1

You should define summartReport taking ostream& as parameter, as shown here:

std::ostream&  storageRentals::summaryReport(std::ostream & out) const
{
    //use out instead of cout
    for (int count = 0; count < 8; count++)
        out << "Unit: " << count + 1 << "    " << stoUnits[count] << endl;

    return out; //return so that op<< can be just one line!
}

then call it as:

ostream& operator <<(ostream& osObject, const storageRentals& rentals)
{
    return rentals.summaryReport(osObject); //just one line!
}

By the way, it is not called "overloading cout". You should say, "overloading operator<< for std::ostream.