sollte klappen:
Code:
<?php
$subjects = [
'',
'123',
'123456789',
'123456789,',
'123456789,123',
'123456789,123456789',
'123456789,123456789,',
];
foreach($subjects as $subject){
var_dump(preg_match('`^([0-9]{9},)+$`', $subject, $matches));
var_dump($matches);
}