Houjun Liu


regular expressions

did you know you can do matching inline too matching equivalent statements: test (\w+) \1; non-capture group (?:test)


  • (?=pattern) true if pattern matches, but doesn’t touch the character pointer
  • (?!pattern) true if pattern doesn’t match; also doesn’t advance pointer
  • (?:pattern) will advance character pointer but will not create a capture group
  • ^beginning of line
  • end of line$