Get words in string as array in PHP

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$input = 'How to split words in string to an array using regex.';
$output = array();
 
preg_match_all('/ (-?)("[^"]+"|[^" ]+)/i', ' ' . $input, $matches, PREG_SET_ORDER);
foreach ($matches as $match) {
  $phrase = false;
  // Strip off phrase quotes.
  if ($match[2]{0} == '"') {
    $match[2] = substr($match[2], 1, -1);
    $phrase = true;
  }
  $words = trim($match[2], ',?!();:-');
  $words = $phrase ? array($words) : preg_split('/ /', $words, -1, PREG_SPLIT_NO_EMPTY);
  foreach ($words as $word) {
    $output[] = trim($word, " ,!?.");
  }
}
Programming Language: PHP