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ostream overloading << must be declared with one parameter error in compile

gbilios
gbilios asked
on
Medium Priority
737 Views
Last Modified: 2012-05-05
i get the following error in compile,
  ostream overloading << must be declared with one parameter error in compile.

this is the program - working on date formatting in c++

#include <iostream>
#include <fstream>
#include <string>

using namespace std;

class date
{

public:

      date(int day = 1, int month = 1, int year = 1940)
{

      this->day = day;
      this->month = month;
      this->year = year;
}

date(const long& date)
{
    year = date/10000;
    if (year < 100)
    {
           year = 1900 + year;
    }
     month = (date % 10000) / 100;
     day = date % 100;
}

void Setdate(date d)
{      
               day=d.GetDay();
                month=d.GetMonth();
              year=d.GetYear();
}      
int GetDay() const
{
     return day;
}

int GetMonth() const
{
     return month;
}

int GetYear() const
     {
return year;
}

date NextDate(date d)
      {
            date ndat;

            ndat=date((d.GetDay()+1),d.GetMonth(),d.GetYear());
            ndat=date(1,(d.GetMonth()+1),d.GetYear());
            ndat = date(1,1,(d.GetYear()+1));

return ndat;
      }

ostream& operator <<(ostream& os, const date& d)
{
      return os << d;
}

void tst_print()
{
      date d;
      cout << d;
}

private:
      int day;
      int month;
      int year;
      static int numOfDays[];
};

int main(void)
{

date d(8,11,2006);

d.tst_print();

return(0);
}
Comment
Watch Question

First of all make it friend
friend ostream& operator <<(ostream& os, const date& d);
>> return os << d;
This will be recursive.
Change this to something like

friend ostream& operator <<(ostream& os, const date& d) {
   return os << d.day << "/" << d.month << "/" << d.year << endl;
}

Or, whatever format you desire.

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>>>> First of all make it friend

FYI:
the main issue for doing so is *not* to have access to private members (what is just an additional benefit) *but* to tell that the overload of operator<< is not a class member but a global function. Overloads of operator<<(ostream& os, ...)  must be made global cause the return value is ostream& and not the class you define. Non-global overloads of operator<< need to return a reference to the own class. Global overloads were needed so that you can mix different outputs, e. g.

   date d = "01/01/2007";
   string s = "Next new year is: ";

   cout << s << d << endl;

Any operand here uses a different overload of operator<<

Regards, Alex
 

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