title: Visual Studio Include cpp file from other project
body: <p>I have a C++ .h and .cpp file from another project that I want to include into my project.
  I don't want to copy the files over into my project since I want any changes to those files be applied to both projects.</p>
  
  <p>I've included the directory of the file's folder in the </p>
  
  <blockquote>
    <p>Properties->VC++ Directories->Include Directories</p>
  </blockquote>
  
  <p>I've also included the folder in the </p>
  
  <blockquote>
    <p>Properties->C/C++ -> General -> Additional Include Directories</p>
  </blockquote>
  
  <p>The .h files seem to work. If I rename the include to anything other than</p>
  
  <blockquote>
    <p>#include "myfile.h"</p>
  </blockquote>
  
  <p>The cpp file gets unknown definitions.</p>
  
  <p>When I compile. The error is </p>
  
  <blockquote>
    <p>fatal error C1083: Cannot open source file: '..\..\..\..\..\..\my project\myfile.cpp': No such file or directory</p>
  </blockquote>
  
  <p>If I remove the cpp file from the project. Then I get a long list of unresolved functions.</p>
  
  <blockquote>
    <p>error LNK2019: unresolved external symbol "public: unsigned long __thiscall myclass::myfunction"</p>
  </blockquote>
  
  <p>How can I include both the .h and .cpp file into my second project?</p>