$re = '/(?:class="priceValue">\s*)(\d*\.\d+)/';
$str = '<tr class="tr_standard"><td>Milk (regular), (1 liter) </td> <td style="text-align: right" class="priceValue"> 2.45 TL</td>';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($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