help, help with regular expression.

[a_k_a_robin]

im about to hang myself,
[^cat] reads "match any characters except c a or t."

how can we force it to read "match any character except c a and t in this exact order. in other words treat cat as a word to match, not as a series of character to match.

help it clear enought, any help will be greatly appreciated.

[a_k_a_robin]

because [^abc] will match those character even if there are other chars in between them. i'm trying to match words instead of chars.

[ednark]

http://us2.php.net/manual/en/reference.pcre.pattern.syntax.php

this might be a useful resource

also 'lookbehind references' might be something you are looking for. i can't tell without more context of what you want to match and where in the string it might be