Standard functions and operations not working in class constructor

Question

I am trying to make my first class with a constructor and it seems to be acting strangely. My class is derived from filebuf and for some reason, I am unable to open it in the constructor. I tried to add a cout statement for debugging, but the << operator is not recognized.

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

int main()
{
    bin myBin("e:\Temp\test.txt");


    system("PAUSE");
    return 0;
}

bin.h

#pragma once
#include <fstream>
#include <cstdlib>
#include <cstring>

class bin : private std::filebuf {

int buffSize = 1000;
char* buffer;
unsigned int length;
short int buffCounter;

public:
    bin(std::string fileName)
    {
        open(fileName.c_str(), std::ios::in | std::ios::out | std::ios::trunc);
        if (!is_open())
            std::cout << "ERROR: failed to open file " << fileName << std::endl;

        //set all IO operations to be unbufferred, buffering will be managed manually
        setbuf(0, 0);
        //create buffer
        buffer = new char[buffSize];

    };


     virtual ~bin()
    {
        delete buffer;
    };
};

Steephen · Answer 1 · 2015-06-13T18:06:00.247

2

bin myBin("e:\Temp\test.txt");

You have to correct above line as follows:

bin myBin("e:\\Temp\\test.txt");

DEMO: http://cpp.sh/7b4k

edited Jun 13 '15 at 18:06

answered Jun 13 '15 at 18:01

Steephen

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I corrected it and I still get the same build error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'std::string' (or there is no acceptable conversion) c:\users\mt\documents\visual studio 2013\projects\cipher\cipher\bin.h 18 – Michael Jun 13 '15 at 18:02
@Person93 please refer the demo, it is working after this change – Steephen Jun 13 '15 at 18:06

score 1 · Answer 2 · answered Jun 13 '15 at 18:04

1

It looks like you need:

#include <iostream>

answered Jun 13 '15 at 18:04

donjuedo

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It's included in the cpp file where the main function is. – Michael Jun 13 '15 at 18:10
@Person93 it is very bad practice to write headers that don't include all their dependencies, since it is *very* easy to mess them up. – o11c Jun 14 '15 at 00:18
I do not intend to use cout in the class, only while debugging. – Michael Jun 14 '15 at 00:25

score 1 · Answer 3 · answered Jun 14 '15 at 15:22

To use std::string you need:

#include <string>

The iostream include may have forward-declared std::string but without the full definition you don't get operator<< (or c_str()).

Some other answerers may be unable to reproduce your problem because different standard libraries might have their iostream fully do #include <string> (this is permitted but not required).

user3476093 · Accepted Answer · 2015-06-14T15:07:39.827

-1

std::cout << "ERROR: failed to open file " << fileName << std::endl;

Should be

std::cout << "ERROR: failed to open file " << fileName.c_str() << std::endl;

std::cout doesn't always accept std::string but does accept const char *

edited Jun 14 '15 at 15:07

answered Jun 13 '15 at 18:05

user3476093

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I am a little confused over this arguement: http://coliru.stacked-crooked.com/a/4168e5b7507e6e42 – Steephen Jun 13 '15 at 18:12
1

Yeah this is totally false, `std::string` has an overloaded [`operator<<`](http://en.cppreference.com/w/cpp/string/basic_string/operator_ltltgtgt) – Barry Jun 13 '15 at 18:17
@Barry - the reason why I put this answer was because the asker of the question put on a comment to Steephen's answer that 'error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'std::string' (or there is no acceptable conversion) c:\users\mt\documents\visual studio 2013\projects\cipher\cipher\bin.h 18' which is why I put this answer. – user3476093 Jun 13 '15 at 18:19

Standard functions and operations not working in class constructor

4 Answers4