Can't understand this error

Code:

// Overide operator >> to read date
std::istream& operator>>(std::istream& in, const Date& date)
{
	in >> date.year;
	in >> date.month;
	in >> date.day;
	in >> date.hour;
	in >> date.minute;
	
	return in;
}

// ERROR: : error C2679: binary '>>' : no operator found which takes a right-hand operand of type 'const int' (or there is no acceptable conversion)

Date Class

Code:

#ifndef DATE_H
#define DATE_H

#include <time.h>
#include <iostream>

class Date						
{
public:

	Date();

	void SetDate(tm curr_tm);
	static tm getCurrentTime();
	int getDay(){return day;}
	int getMonth(){return month;}
	int getYear(){return year;}
	int getHour(){return hour;}
	int getMinute(){return minute;}
	tm getLocalDT(){return local_dt;}
	friend std::istream& operator>>(std::istream& in, const Date& date);
	friend std::ostream& operator<<(std::ostream& out, const Date& date);
	
private:

	int day;
	int month;
	int year;
	int hour;
	int minute;
	tm local_dt;
};


#endif;

???????
All the members of Date are declared as int

Change:

Code:

std::istream& operator>>(std::istream& in, const Date& date)

to:

Code:

std::istream& operator>>(std::istream& in, Date& date)

After all, it does not make sense to try and read into something that you are not allowed to change.

Originally Posted by laserlight

Change:

Code:

std::istream& operator>>(std::istream& in, const Date& date)

to:

Code:

std::istream& operator>>(std::istream& in, Date& date)

After all, it does not make sense to try and read into something that you are not allowed to change.

Interesting that most of the Date examples i've seen have this as a const ...

Other related questions

1. If i do the following i get a 'recursive error which may cause memory overflow'

Code:

// Overide operator >> to read date
std::istream& operator>>(std::istream& in, const Date& date)
{
	in >> date;
	
	return in;
}

Is it also because of const?

2. What's the advantage of having this overloading outside the class as a free function, or like i have it (friend), or have it as static function inside the class?

Originally Posted by csonx_p

Interesting that most of the Date examples i've seen have this as a const ...

Other related questions

1. If i do the following i get a 'recursive error which may cause memory overflow'

Code:

// Overide operator >> to read date
std::istream& operator>>(std::istream& in, const Date& date)
{
	in >> date;
	
	return in;
}

Is it also because of const?

2. What's the advantage of having this overloading outside the class as a free function, or like i have it (friend), or have it as static function inside the class?

No, it's because in >> date is going to call operator >> -- the same operator >> you are defining. You're going to need to break date into its parts and call >> on those.

Originally Posted by csonx_p

Interesting that most of the Date examples i've seen have this as a const ...

Can't comment on that one... It's incorrect to use a const reference to a operator>> since its purpose is to change the content of the second variable.

Other related questions

1. If i do the following i get a 'recursive error which may cause memory overflow'

Code:

// Overide operator >> to read date
std::istream& operator>>(std::istream& in, const Date& date)
{
	in >> date;
	
	return in;
}

Is it also because of const?

Nope, it's because

Code:

	in >> date;

becomes:

Code:

	opertor>>(in, date);

which is the same function you are in - so it's infinitely calling itself until the stack overflows or the application terminates for another reason - most likely the stack will fill up first of those two things (unless you are really quick on the CTRL-C keypress).

2. What's the advantage of having this overloading outside the class as a free function, or like i have it (friend), or have it as static function inside the class?

There isn't much advantage either way - both are valid and generate the same code in the end.

--
Mats

Originally Posted by csonx_p

Interesting that most of the Date examples i've seen have this as a const ...

Perhaps you have been looking at overloading operator<< instead:

Code:

std::ostream& operator<<(std::ostream& out, const Date& date);

Originally Posted by laserlight

Perhaps you have been looking at overloading operator<< instead:

Code:

std::ostream& operator<<(std::ostream& out, const Date& date);

!Oh u right ...