if you don't have to be regular, you don't have to be irregular.
if you have to use it, then

</span>

^$
$matches = -50;
$res = preg_match('/^[1-9]{1,10}$/',$matches);
print_r($res);  //0
 if you just want to use regularity to determine whether it is a negative number, you can do so 
$matches = -50;
$res = preg_match('/-/',$matches);
print_r($res);//1, 
 if the requirement is to determine whether it is a non-negative number, it can also be like this 
$matches = -50;
if(is_numeric($matches) && $matches >= 0) {
    print_r('');
} else {
    print_r('');
}