Search engine - before string and after - php

Question

A have something like this. It works fine, but I have been tried 2 hours to cut search result - 100 str before $word and 100 after.
How can I make this?
$word = $_POST["search"];
$sql_events = mysql_query("SELECT * FROM events WHERE event_title LIKE '%" . $word . "%' OR event_desc LIKE '%" . $word ."%'");
function highlightWords($content, $word){
if(is_array($search)){
foreach ( $search as $word ){
$content = str_ireplace($word1, '<span>'.$word1.'</span>', $content);
}
} else {
$content = str_ireplace($word, '<span>'.$word.'</span>', $content);
}
return $content;
}
while($row = mysql_fetch_array($sql_events)){
$content = $row["event_desc"];
$result = highlightWords($content, $word);
echo '<li>
<H3>'.$row['event_title'].'</H3>
<div class="text">'.$result .'...</div>
</li>';
}

Answer 1

You need this regular expression:
[\d\D]{0,100}word[\d\D]{0,100}
Where word is the main word :). Here it is implemeted with your code:
$content = $row["event_desc"];
$word_in_regexp = quotemeta($content);
preg_match("/[\d\D]{0,100}$word_in_regexp[\d\D]{0,100}/i", $content, $matches);
$content = $matches[0];
We use quotemeta() in case $content contains characters like [, (, \ etc.

Answer 2

$wordpos1 = (mb_strpos($content, $word) - 100);
if ($wordpos1 < 0){
$wordpos1 = 0;
} else {
$wordpos1 = (mb_strpos($content, $word) - 100);
}
$wordpos2 = (mb_strpos($content, $word) + 400);
$resText = mb_substr($content, $wordpos1, $wordpos2);
$result = highlightWords($resText, $word);
And it's works to me :)