Syntaxes
Regular expressions syntaxes are not equivalent across different implementations. New syntaxes can even come along and our study of regular expression here does not need to be polluted by these matters. Therefore, we have arbitrary chosen from popular implementation the syntax used to illustrate our examples.
That said, many remarks are included about less commons features and particularities of some well known implementation.
Depending on the implementation, some features may be missing. Note also that Perl and .NET provide specific solutions for matching nested constructs. We do not illustrate them here for now.
See also...
- Regular expressions - A technical white paper about this powerful language
- Regular Expression Engines - NFA and DFA engines explained
- Regular expressions backtracking and quantifiers greediness - Backtracking of NFA engines explained
- Backtracking in regards to correctness and efficiency - Examples related to backtracking
- Unrolling the loop - Optimize repeated alternation