Binary Overloaded Operator =

Question

Therefore, I am trying to write and read from a file using std::ostream_iteratorand std::iostream_iterator. The recording process works without errors. But as for reading, I'm lost. I have an error:

1> c: \ program files (x86) \ microsoft visual studio 14.0 \ vc \ include \ xutility (2316): error C2678: binary '=': operator not found that accepts a left operand of type 'const WRstruct' (or not acceptable conversion)

and he says that:

c: \ users \ xxxxxxx \ desktop \ ttttt \ ttttt \ wrstruct.h (21): note: maybe 'WRstruct & WRstruct :: operator = (const WRstruct &)' 1> c: \ program files (x86) \ microsoft visual studio 14.0 \ vc \ include \ xutility (2316): note: when trying to match the argument list '(const WRstruct, WRstruct)'

What is the correct way to overload operator=?

class:

#include <iostream>
#include <string>
#include <fstream>
#include <vector>
#include <iterator>
#include <istream>

class WRstruct
{
private:
    std::string name;
    std::string number;
    friend std::ostream& operator<<(std::ostream&, const WRstruct&);
    friend std::istream& operator >> ( std::istream& is, WRstruct&);

public:
    WRstruct(){};
    void write();
    void read();
    ~WRstruct(){};
};
std::ostream& operator<<(std::ostream& os, const WRstruct& p)
{
    os << "User Name: " << p.name << std::endl
        << "Name: " << p.number << std::endl
        << std::endl;
    return os;
}

std::istream& operator >> (std::istream& is, WRstruct& p)
{

    is >> p.name>>p.number;
    return is;
}

Methods

void WRstruct::write()
{
    std::vector<WRstruct> vecP;
    std::copy(std::istream_iterator<WRstruct>(std::cin),
    std::istream_iterator<WRstruct>(), std::back_inserter(vecP));
    std::ofstream temp("temp.txt", std::ios::out);
    std::ostream_iterator<WRstruct>temp_itr(temp, "\n");
    std::copy(vecP.begin(), vecP.end(), temp_itr);

}

void WRstruct::read()
{
    std::vector<WRstruct> vec;

    std::ifstream readFile("temp.txt");
    std::istream_iterator<WRstruct> istr(readFile);
    copy(vec.begin(), vec.end(), istr);

    std::istream_iterator<WRstruct> end_istr;
    copy(istr, end_istr, back_inserter(vec));

    std::ostream_iterator<WRstruct> osIter(std::cout," ");
    copy(vec.begin(),vec.end(),osIter);

}

and main ():

#include <iostream>
#include "WRstruct.h"

int main()
{
    WRstruct r;
    r.write();
    //r.read();

    return 0;
}

Answer 1

As far as I understand, the value of your function WRstruct::readis "reading all the data from" temp.txt "and writing it to the console." By the way, it is strange that a function readprints something, so think about naming your function accordingly.

To read something from a file using istream_iterator, you must create a pair of iterators (one points to the beginning of the file, and the other is empty) and use std::copy. So, part of reading your function should look like

std::vector<WRstruct> vec;

std::ifstream readFile("temp.txt");
std::istream_iterator<WRstruct> istr(readFile);
std::istream_iterator<WRstruct> end_istr;
copy(istr, end_istr, back_inserter(vec));

So you can just comment or delete one line from WRstruct::readto get rid of a compilation error.