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)" in the most efficient manner possible.

So far, the best I've come up with is this:

$fullString = "ignore everything except this (text)"; $start = strpos('(', $fullString); $end = strlen($fullString) - strpos(')', $fullString);  $shortString = substr($fullString, $start, $end); 

Is there a better way to do this? I know in general using regex tends to be less efficient, but unless I can reduce the number of function calls, perhaps this would be the best approach? Thoughts?

Answer 1

i'd just do a regex and get it over with. unless you are doing enough iterations that it becomes a huge performance issue, it's just easier to code (and understand when you look back on it)

$text = 'ignore everything except this (text)'; preg_match('#\((.*?)\)#', $text, $match); print $match[1]; 

Answer 2

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.