* Ulrik Petersen <[EMAIL PROTECTED]> [2006-06-25 17:55]: > 5) Use the function with the regex '[spqd]' to search for words > containing the letters "s", "p", "q", OR "d". Doing it for all > letters (AND) may be doable with a single regex,
It is doable with an NFA engine like PCRE, but it’s complicated to express and will incur so much backtracking that it’ll run much slower than doing four separate matches. With DFA engine such as egrep’s you can’t express it in a single pattern at all. For ultimate performance on strings, you’ll need to walk the string using a loop in a machine-oriented language like C and check characters directly. If you need to go even faster, then you’ll need an inverted index on letters for the whole dataset. Regards, -- Aristotle Pagaltzis // <http://plasmasturm.org/>
