problems with overload operator >>

[Faggio]

I wrote this program. Note that Date is another class that i have implemented.
Compiler finds error in function read of Libretto about "ss >> riga" and in the overload of the oparator >> in Entry class.
Help me pls, i don't know what I have to do !

  #ifndef ENTRY_H_INCLUDED
#define ENTRY_H_INCLUDED
#include "Date.h"
#include <vector>
#include <istream>

template <typename T>
class Entry
{
public:
    Entry(){};
    Entry(Date d, string description, T amount )
    {
        _date=d;
        _description=description;
        _amount=amount;

    }
//getters
Date date () const;
string description ()const;
T amount () const;

string str() const;
 friend istream& operator >>(istream& is, Entry <T> &dest){
        is >> dest._date;
        is.ignore();
        is >> dest._description;
        is.ignore();
        is >> dest._amount;

        return is;
    }


private:
    Date _date;
    string _description;
    T _amount;
};

#ifndef LIBRETTO_H_INCLUDED
#define LIBRETTO_H_INCLUDED
#include "Entry.h"
#include <fstream>
#include <cstring>
template <typename T>
class Libretto
{
public:
    Libretto(){};
    void readFile(string filename);

private:
    vector <Entry <T> > _v;
    ifstream fin;
    int _day,_month,_year;
    string _desc;
    T _amount;

};

template <typename T>
void Libretto<T>::readFile(string filename)
{
    string line;
    stringstream ss;
    Entry <float> riga;
    fin.open(filename.c_str());
    if(!fin.is_open())
    {
        cerr<<"errore!"<<endl;
    }
    while(getline(fin, line))
    {
        ss << line;
        ss >> riga;
        _v.push_back(riga);

    }
    fin.close();
    size_t i;
   for(i=0; i<_v.size(); i++)
   {
       cout<<_v[i].str()<<endl;
   }
}



#endif // LIBRETTO_H_INCLUDED 

[Enoizat]

Hi, Faggio.

It's not easy to give opinions about such a small piece of code that can't even compile, but I'll try to pinpoint a couple of potential issues.

friend istream& operator >>(istream& is, Entry <T> &dest)
If the function is friend, it can't be part of the class. So I think you should move the definition outside the class.

This could help also in the error you get about ss >> riga; .

Other weird things are the fact that you declare for example
string _desc
but you didn't seem to include <string> (but you include <cstring>... to what avail, if I may ask?).

BTW, why do you declare "i" outside the for loop?

size_t i;
for(i=0; i<_v.size(); i++)

Do you have a further use for it?

I'm bound to confess I find it confusing to have functions and variable with the same names, apart from an underscore... Do you find it easy to read? Well, that's just a matter of tastes, I presume.

I think you ought be better not to declare using namespace std; , as you are likely to have done somewhere.

Hope that could be of some help.

[Faggio]

I'm very greatfull for your answer and I understand your difficulties to read this piece of code that is a part of a larger project.
Infact I include <string> in another class(Data) that is included in Entry and ,so , also in Libretto.
I prefer to write the declaration of i outside the for loop.
I try to place the definition of friend function outside the class but it doesn't work.
So i replace the definition inside and i write <float>inside of <T> in friend function: now the only one error that compiler gives me is:
error: no match for 'operator >>' in 'is >> dest._date'

[ne555]

> Compiler finds error
¿what error?

> If the function is friend, it can't be part of the class. So I think you
> should move the definition outside the class.
there is no problem in writing the definition there, and in some cases (like templates) may be preferred.

> now the only one error that compiler gives me is:
> error: no match for 'operator >>' in 'is >> dest._date'
¿have you overloaded the operator>> for Date?


> Infact I include <string> in another class(Data) that is included in Entry
try to avoid that.
Suppose that later `Date' doesn't need string anymore, then you'll get compiler errors in Entry.
If you need to use something, then include the appropriate header.

[Enoizat]

there is no problem in writing the definition there, and in some cases (like templates) may be preferred.

Didn't know that!
Thanks a lot, @ne555, I was giving a wrong answer.

[Faggio]

Thank you a lot @ne555!! I had to overload the operator in Date!!
thank you again!!