title: openfoam: flex yyin.rdbuf(std::cin.rdbuf() error
body: <p>I want to report a solution to an error I
  got while installing OpenFOAM 3.0.1 in Mac OS X El Capitan Version 10.11.2
  The error was:</p>
  
  <blockquote>
    <p>"error: member reference type 'std::istream *' (aka
    'basic_istream *') is a pointer; maybe you meant to use '->'?
                            yyin.rdbuf(std::cin.rdbuf());"</p>
  </blockquote>
  
  <p>This problem is related to <code>flex version 2.6.0</code>. which I installed using macports.</p>
  
  <p>I could overcome the problem by using "<code>flex 2.5.35 Apple(flex-31)</code>" which is at <code>/usr/bin/flex</code> (instead of <code>/opt/local/flex</code>).</p>
  
  <p>Just change "flex" to "/usr/bin/flex" in the file
  $(WM_DIR)/rules/General/flex++
  of your openfoam source distribution.</p>