$re = '/((<b>([a-z]+)<\/b>)((?!<br>).)*)$/im';
$str = '<b>word</b><br>
<b>word</b> <br>
<b>word</b> in text
half<b>word</b> ';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php