title: What does slash in a header file name mean?
body: <p>I was reading the gcc <a href="http://gcc.gnu.org/onlinedocs/cpp/Include-Syntax.html#Include-Syntax" rel="nofollow">gnu-online-docs</a>. I am confused about what it mentions regarding a <code>\</code> or <code>/</code>in a header file name.</p>
  
  <p>It says:</p>
  
  <blockquote>
    <p>However, if backslashes occur within file, they are considered
    ordinary text characters, not escape characters. None of the character
    escape sequences appropriate to string constants in C are processed.
    Thus, <code>#include "x\n\\y"</code> specifies a filename containing three
    backslashes. (Some systems interpret ‘\’ as a pathname separator. All
    of these also interpret ‘<code>/</code>’ the same way. It is most portable to use
    only ‘<code>/</code>’.)</p>
  </blockquote>
  
  <p>What does it mean by "some systems" in this paragraph? Does it mean the implementation depends upon the OS - Windows/Linux? (I know in <code>#include &lt;linux/module.h&gt;</code>, <code>/</code> specifies a path)</p>