making a php concordancer

I want to use PHP to search through a given URL to find a search term, then display the results with some context surrounding each instance of the word that it found. It's for a class, and I'm new to PHP so I apologize for lack of knowledge. Here is what I have so far:

$contents = file_get_contents("http://mcmaster.ca/"); // grab contents
$word = "McMaster"; // define word to search

// match McMaster with word boundaries (\b) and capture offsets
preg_match("/\b$word\b/", $contents);


$next = strpos($contents, $char, $offsets);
$after = substr($contents, ($offsets+strlen($word)), strlen($contents)-$next);

# find string before offset
$beforetext = substr($contents, 0, $offsets);
$last = strrpos($contents, $char);
$before = substr($contents, $last, $offsets-$last);

It appears to be finding the word, but I'm not sure how to make the results display in any coherent way.

 

echo "$before $word $after";

Code (markup):

should do it I think? (if not, your substr calls arent doing what they should be)