highlighting keywords from my search engine

[acidbox]

I wrote a function to highlight keywords from my search engine. The script. It is as follows:

function highlight ($keywords, $string)
	{
		if (!is_array($keywords))
			{
				$keywords = explode(" ", $keywords);
			}

	for ($x = 0; $x < count($keywords); $x++)
		{
			$string = str_replace(addslashes(htmlspecialchars($keywords[$x])), "<span class=\"highlight\">" . addslashes(htmlspecialchars($keywords[$x])) . "</span>", $string);
		}

	return $string;
}

The problem is, for instance, if one of my keywords was span, highlight, or any other word that would appear in the highlighting CSS code. It works fine if there is only 1 keyword, but if there are more, and one happends to occur in the highlighting code, then it breaks.

For Example: if my two keywords are truck and span, the script loops two times, and ends up like this:

I own a red <<span class="highlight">span</span> class="highlight">truck</span>

of course, this looks like crap. How can I get the script to recognize multiple keywords without having the script think that the <span> tag is part of the string on the second pass?

[Oersoep]

Use a regexp.

$dead_body = eregi_replace( '(word1|word2|word3)', '<span>\\1</span>', $victim );

 

\1 is the matched word

Do be careful that the words in the regexps don't contain regexp-like charactes (), {}, ^, [], $, |

[acidbox]

how would I make it so it doesn't try to replace words that are a part of a link? If one of my keywords was http for instance, it will jump in and put the span tags around the http, breaking the link.

[Oersoep]

In that case you'll have to secure any html, scripts and stylesheets you need to do some more handwork. Isolate the text from the html, place the tags, en put it together again.