LNK2019 on a solution with a dll project - c++

Question

I am trying to create a solution which one project is the .exe and the other project is a simple dll. What i am trying to learn is how to link between two projects. I have searched stack-overflow and found really nice answers which I have followed, such as declaring the right header bath on:
Properties->Configuration Properties->C/C++->General->Additional Include Directories
Then setting the .lib on:
Properties->Configuration Properties->Linker->Input->Additional Dependencies
I used macros to generate that .lib file also. Here is the my simplified code:
The .exe:
cpp:
#include "stdafx.h"
#include "../ConsoleApplication2/HelloWorld.h"
int _tmain(int argc, _TCHAR* argv[])
{
hello_world hw;
hw.printHello();
getchar();
return 0;
}
The dll:
header:
#pragma once
#ifdef is_hello_world_dll
#define hello_world_exp __declspec(dllexport)
#else
#define hello_world_exp __declspec(dllimport)
#endif
class hello_world_exp hello_world
{
public:
hello_world();
~hello_world();
void printHello();
};
cpp:
#include "stdafx.h"
#include "HelloWorld.h"
#include <iostream>
hello_world::hello_world()
{
}
hello_world::~hello_world()
{
}
void printHello()
{
std::cout << "Hello World" << std::endl;
}
A note: The solution compiles fine when I don't call hw.printHello(); however when I do call it, the linker generates :
Error 1 error LNK2019: unresolved external symbol "__declspec(dllimport) public: void __thiscall hello_world::printHello(void)" (__imp_?printHello#hello_world##QAEXXZ) referenced in function _wmain C:\Users\usteinfeld\Desktop\Private\Students\Yana\ConsoleApplication1\ConsoleApplication1\ConsoleApplication1.obj ConsoleApplication1

Answer 1

This function is defined as a free function based on how you wrote it
void printHello()
It belongs to the class hello_world so you should scope it as such
void hello_world::printHello()
{
std::cout << "Hello World" << std::endl;
}