(Error C2678) Error: No operator "<<" matches these operands

Question

please note: this has been asked before

so I am trying speed to learn c++, since my clan have ddecided to start writing a game, but I have only done delphi, C#, java

Problem:

I have read through a few posts regarding this issue and as I understand I need to "overload the cout class" for use of the operator "<<" and ">>",

what is the reason for this, and isnt there a easier method for achieving this

the 2 operators (prob x) are giving the issue

// Custom.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include <Windows.h>


int _tmain(int argc, _TCHAR* argv[])
{
    using namespace std;

        double input, out;
        string degtype;

        cin /*>> "What is the temperature: "*/ >> input;
        cin /*>> "Convert to [C]elsius or [F]ahrenheit?: " */ [(prob1)>>] degtype;

        if (degtype.compare("C") == 0 || degtype.compare("c") == 0)
        {
            out = (-32 - (input * 1.8)) + input;
            degtype = "Celcius";
        }
        else
            if (degtype.compare("F") == 0 || degtype.compare("f") == 0)
        {
            out = 32 + (input * 1.8);
            degtype = "Fahrenheit";
        }

            cout << "The " [(prob 2)<<] degtype << "value is " << out;


}

**please note: if this has been asked before, _don't post it again_!** — Lightness Races in Orbit, Jan 11 '14 at 17:32
@LightnessRacesinOrbit The reason of reposting is that the answers to the previous post do not solve the problem, I would like to know the reason for the error and why it happens! — , Jan 11 '14 at 17:35
@juanchopanza thank you, it solved the problem, why would it give the error with strings but not with chars? — , Jan 11 '14 at 17:37
What makes you think that you can't create a game in C# or Java? — molbdnilo, Jan 11 '14 at 18:03
`` contains the operators required for streaming built-in types to `std::cout`. It makes no promises about `std::string`. I think this is covered in the duplicates. — juanchopanza, Jan 11 '14 at 18:42
@user2699451: Yeah, they do. I wrote one of those answers. It's basically the same as the one I wrote below that you accepted! — Lightness Races in Orbit, Jan 12 '14 at 12:36

score 4 · Accepted Answer · answered Jan 11 '14 at 17:34

what is the reason for this

As already explained in the duplicates you admit exist, the reason is that you did not include the proper header that provides all the string functionality.

Half of it appeared to work by pure chance, because some other standard headers included little bits for you, in order to do their own work.

and isnt there a easier method for achieving this

No. Really, this could not be easier:

#include <string>

Write that.

That's it.

(Error C2678) Error: No operator "<<" matches these operands

1 Answers1