parse search string for phrases and keywords

Question

i need to parse a search string for keywords and phrases in php, for example

string 1: value of \"measured response\" detect goal \"method valuation\" study

Answer 1

$s = 'value of "measured response" detect goal "method valuation" study';
preg_match_all('~(?|"([^"]+)"|(\S+))~', $s, $matches);
print_r($matches[1]);

output:

Array
(
    [0] => value
    [1] => of
    [2] => measured response
    [3] => detect
    [4] => goal
    [5] => method valuation
    [6] => study
)

The trick here is to use a branch-reset group: (?|...|...). It's just like an alternation contained in a non-capturing group - (?:...|...) - except that within each branch the capturing-group numbers start at the same number. (For more info, see the PCRE docs and search for DUPLICATE SUBPATTERN NUMBERS.)

Thus, the text we're interested in is always captured group #1. You can retrieve the contents of group #1 for all matches via $matches[1]. (That's assuming the PREG_PATTERN_ORDER flag is set; I didn't specify it like @FailedDev did because it's the default. See the PHP docs for details.)