Web Dev Blog

I recently came across the need to efficiently parse a string and find what was in between two “marker” strings. I was parsing a logfile with a particular preset format. The line looked like this:

$str = '2008-10-07_00:00:19 - ip:[213.21.198.231] page:[/phpsimplechat/documentation_usage.php]';

I wanted to be able to easily pull out the ip and page information in a straight-forward way without repeating code. After a little tinkering I came up with a get_token() function that accomplished my goal nicely. The function is below:

function get_token($start_token, $end_token, $haystack, $offset = 0) {
 
	$start = stripos($haystack, $start_token, $offset);
	$end = stripos(substr($haystack, $start), $end_token);
 
	if ($start !== false && $end !== false) {
		$start_pos = $start + strlen($start_token);
		$end_pos = $end - strlen($end_token);
		return substr($haystack, $start_pos, $end_pos);
	}
	return false;
}

Let’s take my above example – if I want to pull out the ip and page information from the given string, I only need to implement the below code:

$str = '2008-10-07_00:00:19 - ip:[213.21.198.231] page:[/phpsimplechat/documentation_usage.php]';
$ip = get_token('ip:[', ']', $str);
$page = get_token('page:[', ']', $str);

The optional offset argument allows you to specify how many characters into the $haystack that you want to start looking;

Here is another example usage in which we want to pull the title out of some HTML code.

$str = 'This is the body';
$title = get_token('', $str);