title: Is a C++ preprocessor identical to a C preprocessor?
body: <p>I am wondering how different the preprocessors for C++ and <strong>C</strong> are.</p>
  
  <p>The reason for the question is <a href="https://stackoverflow.com/questions/5085392/what-is-the-value-of-an-undefined-constant-used-in-if-c">this question</a> on a preprocessor-specific question where the paragraph of the standard that addresses the question has a different wording (and a different paragraph number) and also are difference concerning the <code>true</code> and <code>false</code> keywords in C++.</p>
  
  <p>So, are there more differences or is this the only difference.</p>
  
  <p>An extension of the question would be when is a source file emitted differently by a C++ preprocessor and a <strong>C</strong> preprocessor.</p>