$re = '/^[a-z A-Z]+\d{0,5} ?[a-zA-Z]?/m';
$str = 'Oslo gate 20
Oslo gate 39a
Oslo gate 39 a
Oslo Gate
Oslo
30
Oslo gate49a
Oslo gate 39a
Oslo gate 34a, leil. H0205
leil. H0205, Oslo gate 34a';
preg_match_all($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