title: C++ - /tmp/cckpbRW.o:main.cc:(.text+0x9d):undefined reference
body: <p>Following the example here: <a href="http://www.learncpp.com/cpp-tutorial/19-header-files/" rel="nofollow">http://www.learncpp.com/cpp-tutorial/19-header-files/</a></p>
  
  <p>Relating to <code>add.h</code> and <code>main.cpp</code></p>
  
  <p>When I try to compile main.cc (I just used another extension), I get the following:</p>
  
  <pre><code>/tmp/cckpbRW.o:main.cc:(.text+0x9d):undefined reference to 'add(int, int)' collect2: ld returned 1 exit status
  </code></pre>
  
  <p>How can I fix this issue?</p>
  
  <p>Thanks.</p>