$re = '/^(?=.*[[:alpha:]].*)([[:alpha:]]*(\d+([.,]\d+)?)?[[:alpha:]]*)*$/imu';
$str = 'teste123
123teste
teste123teste
0,123teste123.123
t3st3
123olá
olá123
olá0.123
olá.123
o1l2á
café
maça';
preg_match_all($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