[C++] error LNK2019: unresolved external symbol "public: __thiscall kwaternion::~kwaternion(void)"

#include "stdafx.h"
#include <iostream>
#include <cstdlib>
using namespace std;

class kwaternion
{
   
public:
    float re, i, j, k;
    kwaternion()
    {
        re = 0;
        i = 0;
        j = 0;
        k = 0;
    }
   
    kwaternion( float a, float b, float c, float d )
    {
        this->re = a;
        this->i = b;
        this->j = c;
        this->k = d;
    }
    ~kwaternion();
    kwaternion operator +( const kwaternion & l1 );
   
   
    ostream & operator <<( kwaternion & l1 );
   
   
};


ostream & operator <<( ostream & out, kwaternion & l1 )
{
    out << l1.re << l1.i << "i" << l1.j << "j" << l1.k << "k";
    return out;
}


kwaternion kwaternion::operator +( const kwaternion & l1 )

{
    kwaternion dodaj;
    dodaj.re = re + l1.re;
    dodaj.i = i + l1.i;
    dodaj.j = j + l1.j;
    dodaj.k = k + l1.k;
    return dodaj;
}





int main()
{
    kwaternion kw1( 1, 2, 3, 4 );
    kwaternion kw2( 7, 8, 9, 1 );
    kwaternion kw3 = kw1 + kw2;
    cout << kw3 << endl;
   
    return 0;
}