$re = '/{\ ?{\ ?(\d+)\ ?}\ ?}/m';
$str = '{{111}}
{ {111}}
{ { 111}}
{{ 111}}
{{111 } }
{{111} }';
preg_match_all($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