explode won't do the trick nicely for html tags (considering them as multiple delimiters).

if CPU time is not a concern, try using preg_match, example below:

<?PHP

$input='<li>text1</li><li>text2</li><LI><p>text3</p></lI><Li>text fou4r</li>';

preg_match_all('(<(li|Li|LI|lI)>(.*)</(li|Li|LI|lI)>)siU', $input, $output);

print_r($output[2]);
?>

output:

Array

    (

        [0] => text1
        [1] => text2
        [2] => <p>text3</p>
        [3] => text fou4r
    )

if you have all your words in a text file, one per line you can use the file function which will read the whole file into an array, one item per line

http://nz.php.net/manual/en/function.file.php

Check this PHP code :

<?php
  $var = array(5, 7, 9, 10);
  $data = json_encode($var) ;
  echo $data ; //[5,7,9,10]
?>

Use

preg_split

to select just the values and put it in to an array

example:

$keywords = preg_split("/[\s,]+/", $str);

Just change the pattern!

check the documentation: http://php.net/manual/en/function.preg-split.php