Undefined reference to

[ted_kingdom]

When building the program I get the following error: undefined reference to `Atom:: DoBCC(float, int, int, int)'. What am I doing wrong? Thanks in advance.

main.cpp

#include <iostream>
#include "Atom.h"
 
using std::cout;
using std::cin;
using std::endl;
 
int main ()
{
    int latticeType;
    int dimX, dimY, dimZ; // number of translated lattices along each axis
    float d; // lattice parameter
    Atom myAtom; // object of class Atom
 
    cout << "Please choose the crystal lattice." << endl;
    cout << "Type 1 for BCC, 2 for FCC, and 3 for HCP:" << endl;
    cin >> latticeType; // read lattice type
    cout << "Please enter lattice parameter:" << endl;
    cin >> d;
    cout << "Please enter the number of translated lattices along X axis:" << endl;
    cin >> dimX;
    cout << "Please enter the number of translated lattices along Y axis:" << endl;
    cin >> dimY;
    cout << "Please enter the number of translated lattices along Z axis:" << endl;
    cin >> dimZ;
 
    if (latticeType==1) myAtom.DoBCC ( d, dimX, dimY, dimZ ); // if 1, create BCC lattice
    else
    {
        cout << "Invalid value" << endl;
        return 0;
    }
 
    return 0;
}

Atom.h

class Atom
{
    public:
        void DoBCC ( float, int, int, int );
    private:
        float x, y, z;
};

Atom.cpp

#include <iostream>
#include "Atom.h"
 
using std::cout;
using std::cin;
using std::endl;
 
typedef class Atom AtomType;
 
void Atom::DoBCC ( float d, int dimX, int dimY, int dimZ ) // beginning of the DoBCC function
{
    float a = d; // lattice parameter
    int Lx = dimX;
    int Ly = dimY;
    int Lz = dimZ; // number of translated lattices along each axis
 
   // from now on I work with a, Lx, Ly, Lz variables
 
} // end of the DoBCC function