php - How to set NULL if REGEX doesn't has any matches? -

i have regex returns numbers string:

$str  = "this 1 str, 2"; $numb = preg_replace("/[^0-9]/","",$str); echo $numb; // output: 12

but if string doesn't containing number, return nothing. want returns null if string isn't containing number. this:

$str  = "this 1 str"; $numb = preg_replace("/[^0-9]/","",$str); echo $numb; // current output:             // want: null

note: null isn't string, should this: $numb = null;

how can that?

you can't just using regex (since preg_replace returns string or null if encountered error) . need check variable , assign null if needed:

$numb = $numb ?: null;

If code