negative lookahead

English

Etymology

negative +‎ lookahead

Noun

negative lookahead (countable and uncountable, plural negative lookaheads)

1. (regular expressions) The analysis of the subsequent characters absence before the regular expression is matched (symbol: ?!).
   • 2012 August, Jan Goyvaerts, Steven Levithan, Regular Expressions Cookbook:

     Negative lookahead works just like positive lookahead, except that whereas positive lookahead matches when the regex inside the lookahead matches, negative lookahead matches when the regex inside the lookahead failed to match.

Hypernyms

• lookaround
  • lookahead