title: How to build and run C++ API demos in gmsh?
body: <p>I want to use gmsh C++ API to develop software.</p>
  
  <p>I can build the project using cmake from source file on Ubuntu and get a executable file "gmsh".</p>
  
  <p>My problem is:</p>
  
  <ol>
  <li><p>How to compile the program as a shared library?</p></li>
  <li><p>How to compile C++ API demos with the shared library and run it?</p></li>
  </ol>
  
  <p>May be it is a stupid problems, but I have trapped here for hours.</p>
  
  <p>Is there any step by step instructions can help me?</p>