title: When should I not split my code into header and source files?
body: <p>I know this maybe quite subjective, but are there any general rules for situations when it is not necessary for code to be split into two files?</p>
  
  <p>For example is the class is extremely small, or if the file simply holds some global definitions or static functions? Also, in these cases, should the single file be a .cpp file or a .h file?</p>