parse search string for phrases and keywords

preg_match_all('/(?<!")\b\w+\b|(?<=")\b[^"]+/', $subject, $result, PREG_PATTERN_ORDER);for ($i = 0; $i < count($result[0]); $i++) {    # Matched text = $result[0][$i];}

This should yield the results you are looking for.

Explanation :

# (?<!")\b\w+\b|(?<=")\b[^"]+# # Match either the regular expression below (attempting the next alternative only if this one fails) «(?<!")\b\w+\b»#    Assert that it is impossible to match the regex below with the match ending at this position (negative lookbehind) «(?<!")»#       Match the character “"” literally «"»#    Assert position at a word boundary «\b»#    Match a single character that is a “word character” (letters, digits, etc.) «\w+»#       Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»#    Assert position at a word boundary «\b»# Or match regular expression number 2 below (the entire match attempt fails if this one fails to match) «(?<=")\b[^"]+»#    Assert that the regex below can be matched, with the match ending at this position (positive lookbehind) «(?<=")»#       Match the character “"” literally «"»#    Assert position at a word boundary «\b»#    Match any character that is NOT a “"” «[^"]+»#       Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»

There is no need to use a regular expression, the built in function str_getcsv can be used to explode a string with any given delimiter, enclosure and escape characters.

Really it is as simple as.

// where $string is the string to parse$array = str_getcsv($string, ' ', '"'); 

$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.)