title: Are Java and C# regular expressions compatible?
body: <p>Both languages claim to use Perl style regular expressions. If I have one language test a regular expression for validity, will it work in the other? Where do the regular expression syntaxes differ? </p>
  
  <p>The use case here is a C# (.NET) UI talking to an eventual Java back end implementation that will use the regex to match data. </p>
  
  <p>Note that I only need to worry about matching, not about extracting portions of the matched data. </p>