note 19254 added to ref.regex

It's easy to exclude characters but excluding words with a regular expression is a bit more tricky. For parentheses there is no equivalent to the ^ for brackets. The only way I've found to exclude a string is to proceed by inverse logic: accept all the words that do NOT correspond to the string. So if you want to accept all strings except those _begining_ with "abc", you'd have to accept any string that matches one of the following: ^(ab[^c]) ^(a[^b]c) ^(a[^b][^c]) ^([^a]bc) ^([^a]b[^c]) ^([^a][^b]c) ^([^a][^b][^c]) which, put together, gives the regex ^(ab[^c]|a[^b]c|a[^b][^c]|[^a]bc|[^a]b[^c]|[^a][^b]c|[^a][^b][^c]) Note that this won't work to detect the word "abc" anywhere in a string. You need to have some way of anchoring the inverse word match like: ^(a[^b]|[^a]b|[^a][^b]) ;"ab" not at begining of line or: (a[^b]|[^a]b|[^a][^b])& ;"ab" not at end of line or: 123(a[^b]|[^a]b|[^a][^b]) ;"ab" not after "123" I don't know why "(abc){0,0}" is an invalid synthax. It would've made all this much simpler. Slightly off-topic, here's a regex date validator (format yyyy-mm-dd, remove all spaces and linefeeds): ^(19|20)([0-9]{2}-((0[13-9]|1[0-2])-(0[1-9]|[12][0-9]|30)| (0[13578]|1[02])-31|02-(0[1-9]|1[0-9]|2[0-8]))|([2468]0| [02468][48]|[13579][26])-02-29)$ -- http://www.php.net/manual/en/ref.regex.php http://master.php.net/manage/user-notes.php?action=edit+19254 http://master.php.net/manage/user-notes.php?action=delete+19254 http://master.php.net/manage/user-notes.php?action=reject+19254