[Dev-C++] no match for istream & >> {unknown type}

[softnasolutions-ltd.fsbusiness.co.uk <so...@so...>]

Hi all,

I'm writing a program which reads and calculates students grades. I have =
a Student_info struct with its member functions in a Student_info.h.

when i compile, i get the error=20
no match for istream & >> {unknown type}

in the Student_info.cpp file. Can anyone help me. The definition for the =
problem funtion is=20

istream& Student_info::read(istream& is)
  {
         //read and store the student's name and midterm and final exams =
grades
         is >> name >> midterm >> final;
        =20
         read_hw(is, homework);    //read and store all the stud =
homework grades
         return is;
  }

BELOW IS THE HEADER FILE;

#ifndef GUARD_Student_info_h
#define GUARD_Student_info_h

// Student_info.h header file
#include <iostream>
#include <stdlib.h>
#include <string>
#include <vector>

class Student_info {
public:
       Student_info();
       Student_info(std::istream&);
       std::string name() const {return n;}
       bool valid() const {return !homework.empty();}
       std::istream& read(std::istream&);
       double grade() const;
private:
      std::string n;
      double midterm, final;
      std::vector<double> homework;
};

bool compare(const Student_info&, const Student_info&);
//std::istream& read(std::istream&, Student_info&);
std::istream& read_hw(std::istream&, std::vector<double>&);
#endif

Napoleon.