too long

Question

This question already has an answer here:

• How to validate that a string only contain lowercase letters? 3 answers

I have a regex, which is: /[0-9]+(,[0-9]+)*/.

It accepts only numbers, separated by a comma. For instance:

1,2,3,4 = good
,1,2,3,4 = bad
1,2,3,4, = bad
String = bad

But it also accepts a numbers with a space:

1, 2, 3, 4 = good

How to make regex that wouldn't allow to do so and would only let to enter a numbers, separated by a comma without spaces?

</div>

Answer 1

Your regex is correct as is, you just need to use anchors so you check the full string, and not a partial match.

^[0-9]+(,[0-9]+)*$

https://regex101.com/r/zU22VX/1/

An alternative approach could be:

$string = '1,2,3,4';
$array = str_getcsv($string);
foreach($array as $number) {
    if(!is_numeric($number)) {
        echo 'Bad value' . $number;
        break;
    }
}