string difference

[cody7]

Hi Gurus

Please help me figure this out

$filter = array("just","very short", "long", "two words", "other"); // this list is about 400 array content
$str1 = "This is just a sample text, a very short one";
$str2 = str_replace($filter, "", $str1);

So when I echo $str2

"This is a sample text, a one"

My Question is. what is the best way to know what word(s) from $filter is present in $str1, since str_replace will only return the changed value. for this example ("just","very short") are the words I want to store in an array

Array
(
    [0] => just
    [1] => very short
)

Please note that I am only using PHP4.
Feel free to change the technique if you have other method of extracting the words given above.

Thank you for all your help

[cahva]

Well if you just want to know if something matches in the array, this is one possibility:

$filter = array("just","very short", "long", "two words", "other"); // this list is about 400 array content
$str1 = "This is just a sample text, a very short one";

$found_words = array();
foreach($filter as $v)
{
	if (strpos($str1,$v) !== false)
	{
		$found_words[] = $v;
	}
}

var_dump($found_words);