highlight multiple word from file on php?

Question

I got a file filter.txt with words that I want to highlight on a string.

Filter.txt: test1 test2

My solution doesen't work:

    <?php
    $file = file_get_contents('/home/user/filter.txt', true);
    $keyword=$file;
    $str="This is a test1 and test2 and test3";

    $keyword = implode('|',explode(' ',preg_quote($keyword)));
    $str = preg_replace("/($keyword)/i","<b>$0</b>",$str);
    echo $str;
    ?>

Anyone?

Answer 1

took me like 15 mins but I eventually got it :)

<?php
  $file     = file_get_contents('/home/user/filter.txt', true);
  $keywords = $file;
  $str      = "This is a test1 and test2 and test3";
  $keywords = explode(" ", $keywords);
  $str      = preg_replace('/'.implode('|', $keywords).'/', '<b>$0</b>', $str);
  echo $str;
?>

and this is expecting your filter.txt to be laid out like test1 test2 test3 etc. I'd suggest separating by new line or a pipe, |