Q:

simple program wont compile

Please take a look at my code. The error I get in Visual Studio is
error LNK2019: unresolved external symbol "public: int __thiscall Employee::getId(void)" (?getId@Employee@@QAEHXZ) referenced in function _main

Employee.h
#ifndef EMPLOYEES
#define EMPLOYEES

#include <string>
#include <iostream>
using namespace std;

class Employee
{
private:
    string name;
    int id;
public:
    Employee();
    Employee(string nm, int idd);
    string getName();
    int getId();
};

#endif

Employee.cpp
#include "Employee.h"
#include <string>

Employee::Employee()
{
    name="unknown";
    id=0;
}

Employee::Employee(string nm, int idd)
{
    name=nm;
    id=idd;
}

string Employee::getName()
{
    return name;
}

int Employee::getId()
{
    return id;
}

driver
#include <iostream>
#include <string>
#include "Employee.h"
using namespace std;

int main()
{   
    Employee bob("bob", 3);
    cout << bob.getId();
}

A:

Looks like you forgot to link the two files together. Make sure that you're linking Employee.cpp and  main.cpp files together. Are they added to the same VS project?
EDIT: check out this link. It's outdated, but looks like you did not make a project that contains all the files. They should be linked automagically.

