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

function getStringsBetween($str, $start='[', $end=']', $with_from_to=true){
$arr = [];
$last_pos = 0;
$last_pos = strpos($str, $start, $last_pos);
while ($last_pos !== false) {
    $t = strpos($str, $end, $last_pos);
    $arr[] = ($with_from_to ? $start : '').substr($str, $last_pos + 1, $t - $last_pos - 1).($with_from_to ? $end : '');
    $last_pos = strpos($str, $start, $last_pos+1);
}
return $arr; }

this is a little improvement to the previous answer that will return all patterns in array form:

getStringsBetween('[T]his[] is [test] string [pattern]') will return:

Answer 2

Use a regular expression:

if( preg_match( '!\(([^\)]+)\)!', $text, $match ) )
    $text = $match[1];

Answer 3

i think this is the fastest way to get the words between the first parenthesis in a string.

$string = 'ignore everything except this (text)';
$string = explode(')', (explode('(', $string)[1]))[0];
echo $string;

Answer 4

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 5

This function may be useful.

    public static function getStringBetween($str,$from,$to, $withFromAndTo = false)
    {
       $sub = substr($str, strpos($str,$from)+strlen($from),strlen($str));
       if ($withFromAndTo)
         return $from . substr($sub,0, strrpos($sub,$to)) . $to;
       else
         return substr($sub,0, strrpos($sub,$to));
    }
    $inputString = "ignore everything except this (text)";
    $outputString = getStringBetween($inputString, '(', ')'));
    echo $outputString; 
    //output will be test

    $outputString = getStringBetween($inputString, '(', ')', true));
    echo $outputString; 
    //output will be (test)

strpos() => which is used to find the position of first occurance in a string.

strrpos() => which is used to find the position of first occurance in a string.

Answer 6

The already posted regex solutions - \((.*?)\) and \(([^\)]+)\) - do not return the innermost strings between an open and close brackets. If a string is Text (abc(xyz 123) they both return a (abc(xyz 123) as a whole match, and not (xyz 123).

The pattern that matches substrings (use with preg_match to fetch the first and preg_match_all to fetch all occurrences) in parentheses without other open and close parentheses in between is, if the match should include parentheses:

\([^()]*\)

Or, you want to get values without parentheses:

\(([^()]*)\)        // get Group 1 values after a successful call to preg_match_all, see code below
\(\K[^()]*(?=\))    // this and the one below get the values without parentheses as whole matches 
(?<=\()[^()]*(?=\)) // less efficient, not recommended

Replace * with + if there must be at least 1 char between ( and ).

Details:

• \( - an opening round bracket (must be escaped to denote a literal parenthesis as it is used outside a character class)
• [^()]* - zero or more characters other than ( and ) (note these ( and ) do not have to be escaped inside a character class as inside it, ( and ) cannot be used to specify a grouping and are treated as literal parentheses)
• \) - a closing round bracket (must be escaped to denote a literal parenthesis as it is used outside a character class).

The \(\K part in an alternative regex matches ( and omits from the match value (with the \K match reset operator). (?<=\() is a positive lookbehind that requires a ( to appear immediately to the left of the current location, but the ( is not added to the match value since lookbehind (lookaround) patterns are not consuming. (?=\() is a positive lookahead that requires a ) char to appear immediately to the right of the current location.

PHP code:

$fullString = 'ignore everything except this (text) and (that (text here))';
if (preg_match_all('~\(([^()]*)\)~', $fullString, $matches)) {
    print_r($matches[0]); // Get whole match values
    print_r($matches[1]); // Get Group 1 values
}

Output:

Array ( [0] => (text)  [1] => (text here) )
Array ( [0] => text    [1] => text here   )