title: How to define and declare global variables for use by library code?
body: <p>main file (prog.c):</p>
  
  <pre><code>#include "log.c"
  #include "library.c"
  static char * Foo;
  </code></pre>
  
  <p>If some variable (char * Foo) is defined in main file (prog.c), and it is required by log.c function called from library.c, how to correctly declare Foo to be visible from log.c's namespace?</p>