PHP: Best way to extract text within parenthesis?

Question

What\'s the best/most efficient way to extract text set between parenthesis? Say I wanted to get the string \"text\" from the string \"ignore everything except this (text)\"

Answer 1

So, actually, the code you posted doesn't work: substr()'s parameters are $string, $start and $length, and strpos()'s parameters are $haystack, $needle. Slightly modified:

$str = "ignore everything except this (text)";
$start  = strpos($str, '(');
$end    = strpos($str, ')', $start + 1);
$length = $end - $start;
$result = substr($str, $start + 1, $length - 1);

Some subtleties: I used $start + 1 in the offset parameter in order to help PHP out while doing the strpos() search on the second parenthesis; we increment $start one and reduce $length to exclude the parentheses from the match.

Also, there's no error checking in this code: you'll want to make sure $start and $end do not === false before performing the substr.

As for using strpos/substr versus regex; performance-wise, this code will beat a regular expression hands down. It's a little wordier though. I eat and breathe strpos/substr, so I don't mind this too much, but someone else may prefer the compactness of a regex.