title: cmath vs math.h (And similar c-prefixed vs .h extension headers)
body: <p>I've seen some information about differences between things like <code>iostream</code> vs <code>iostream.h</code>. From what I gathered from those the difference between them is that the version without the <code>.h</code> extension will not populate the namespace while the version with the extension will.</p>
  
  <p>Is this the same for <code>cmath</code> vs <code>math.h</code>? Why is <code>cmath</code> (and many other files like it) prefixed with a <code>c</code> instead of just being <code>math</code>? Are there more differences between them?</p>