Explanation for PHP preg_match_all matches array print_r -

i have following usage preg_match_all:

$re = "/^(-\\w+\\s*.*)\\n*$/um";  $str = "-give on result\n-second new text\n-the third text\n\nanother paragraph without list.\n\n-new list here";  preg_match_all($re, $str, $matches); 

the output of print_r($matches) has weird array:

array (     [0] => array         (             [0] => -give on result             [1] => -second new text             [2] => -the third text              [3] => -new list here         )      [1] => array         (             [0] => -give on result             [1] => -second new text             [2] => -the third text             [3] => -new list here         )  ) 

here i'm talking array of index 0 , visually blank line appeared in print_r() output. indeed, question may related my question regex , need know why 2 arrays different? online demo found here

try easy make that

<?php  //$re = "/^(-\\w+\\s*.*)\\n*$/um";  $re = "/^(\\h*(?:-|&)\\h*\w+\\s*.*)\\n*$/um"; $str = "-give on result\n-second new text\n-the third text\n\nanother paragraph without list.\n\n-new list here";  preg_match_all($re, $str, $matches); echo "<pre>"; print_r($matches); echo "</pre>"; $i = 0;       echo "<ul>".preg_replace_callback($re,function($mt){return "<li>".$mt[1]."</li>";},$str)."</ul>";    $re = array_filter(preg_split('/\n/', $str));  echo "<pre>"; print_r($re); echo "</pre>";