My current commenting style, although it needs work. You'll have to excuse it's JavaScript-iness, that's all I have handy.

// ========================================================
//       COUNT OCCURRENCES (
//                          STR, // String to search through
//                          SUB  // String to search for
//                         )
// --------------------------------------------------------
//   Counts the instances of SUB in STR. Counts overlapping 
//     occurrences.  Count_Occurrences( 'rrrrr', 'rr') = 4.
// --------------------------------------------------------
function Count_Occurrences ( STR, SUB ) {
 var last   = 0;
 var count  = 0; 
 while ((last = STR.indexOf(SUB, last + 1)) > -1) { count++ }
 return count;  
}
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Update: If you ever spend a year in a country where they don't speak your language, keep a spell checker handy. Alternatively, if my code is used it will only be by non-english speakers, who wouldn't know how to spell 'occurrence' anyway. ;)

-Lexicon