C++ .cpp file do not see variables from .h

Question

I have written program in c++. First I have wrote it normally (normally I do not write in c++) and I wanted put variables in header and code in .cpp file. The problem is that class in .cpp do not see variales - "Identifier is undefined".

a.h

#include <iostream>
#include <string>
#include <cmath>
#include <vector>

using namespace std;

class Hex {

private:
    int n;
    string value;
    bool negative = false;

public:
     Hex();
     bool isCorrect();
     string getValue();
     void setValue();
};

a.cpp

#include "a.h"
#include "stdafx.h"     

class Hex {

    public:
      Hex(int n, string w) { //some implementation }

//rest class
}

What I'm doing wrong? If it is important I'm working on VS 2013.

Answer 1

You're defining your class twice, once in the header file and the once in the .cpp file. Assuming you want to just declare functions in the header file and define them in the .cpp file this is the way to go : header:

#include <iostream>
#include <string>
#include <cmath>
#include <vector>

using namespace std;

class Hex {

private:
    int n;
    string value;
    bool negative;

public:
     Hex(int n, string w);
     bool isCorrect();
     string getValue();
     void setValue();
};

.cpp file:

#include "a.h"
#include "stdafx.h"     
Hex::Hex(int n, string w) : negative(false) { /*some implementation*/ }
//rest class and definitions of bool isCorrect(); string getValue(); void setValue();

Answer 2

In the header you're declaring it as Hex(); but in the .cpp you're declaring it as Hex(int n, string w)

Also why not defining it like this Hex::Hex(){//some implementation }