Question

I’m trying to validate a string which contains numbers where each four numbers are separated by a hyphen, for example 1111-2222-3333-4444

I’m trying to do some kind of validating so I can guarantee that this format is being used (with 16 digits, three hyphens and nothing else). I’ve this preg_match where it checks for digits only but I need to accept hyphens and this format.

preg_match('/^[0-9]{1,}$/', $validatenumbers)

I’ve tried to do it with regex but unfortunately it isn’t my strongest side so I haven’t been able to correctly validate the numbers.

It is important that it is in PHP and not Javascript because of the ability to “turn off” javascript in a browser.

Answer 1

preg_match("/^([0-9]{4}-){3}[0-9]{4}$/", $input);

([0-9]{4}-){3} Matches exactly 3 groups of 4 digits followed by a hyphen. That is terminated by another group [0-9]{4} (4 digits without a hyphen).