Oct 15, 2009 · May I know what ?= means in a regular expression? For example, what is its significance in this expression: (?=.*\\d).

What's the difference between () and [] in regular expression patterns? Asked 15 years, 3 months ago Modified 2 years, 10 months ago Viewed 145k times

What are ^.* and .*$ in regular expressions? Asked 14 years, 1 month ago Modified 2 years, 7 months ago Viewed 233k times

A regular expression can only act as a rudimentary filter. The problem with regular expressions is that telling someone that their perfectly valid e-mail address is invalid (a false negative) …

Aug 25, 2012 · I need a regular expression that validates a number, but doesn't require a digit after the decimal. ie. 123 123. 123.4 would all be valid 123.. would be invalid Any would be …

Jul 6, 2009 · 36 Regular expressions first came around in mathematics and automata theory. A regular expression is simply something which defines a regular language. Without going too …

The order is always implied in the structure of the regular expression. To accomplish what you want, you'll have to match the input string multiple times against different expressions.

May 15, 2010 · What does \d+ mean in a regular expression? Asked 15 years, 8 months ago Modified 3 years, 4 months ago Viewed 286k times

Mar 8, 2010 · I know that the following regex will match "red", "green", or "blue". red|green|blue Is there a straightforward way of making it match everything except several specified strings?

A regular expression-agnostic colleague notified me this discussion, which is not certainly the first on the web about this old and hot topic. After reading some posts, the first thing I did was …