Please don\'t answer the obvious, but what are the limit signs that tell us a problem should not be solved using regular expressions?
For example: Why is a complete emai
Regular expressions are suited for tokenizing, finding or identifying individual bits of text, e.g. finding keywords, strings, comments, etc. in source code.
Regular expressions are not suited for determining the relationship between multiple bits of text, e.g. finding a block of source code with properly paired braces. You need a parser for that. The parser can use regular expressions for tokenizing the input, while the parser itself determines how the different regex matches fit together.
Essentially, you're going to far with your regular expressions if you start thinking about "balancing groups" (.NET's capture group subtraction feature) or "recursion" (Perl 5.10 and PCRE).