How to check in PHP8 if a unknown variable (e.g. e-mail) is in a string?

Question

I usually checked this with the following code:

$email = '/[^@:="\'\s]*@[^@\s]*\.[a-z]+/iU';
if(preg_match($email,$article->text) == true) {
to something
}

In PHP 8 this is deprecated (Works, but with warning), because I can't always guarantee that there really is an email in it.

Passing null to parameter #2 ($subject) of type string is deprecated

What are the alternatives?

I know that this solution still works, but I want to be fit for the future.

When searching, I did not find a solution. "str_contains" seems to allow only one string.

"I can't always guarantee that there really is an email in it" - what does that mean? Why can't you check whether `$email` is a defined variable or not? — Nico Haase, Nov 25 '22 at 11:02
There're a few things that can go wrong with that snippet (`$email` not being a valid regular expression, `$article` being `null`, `$email->text` being `null`...) Are you getting an error message? Is your set up configured to display them? — Álvaro González, Nov 25 '22 at 11:41
THANK YOU! Because e-mail is a regexp. I will add this to the code example. — Gratia-Mira, Nov 25 '22 at 11:43
Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in C:\xampp\htdocs\n-edne\plugins\content\protectemail\protectemail.php on line 15 — Gratia-Mira, Nov 25 '22 at 11:49
Sounds like `$article->text` is null. Why not check for that? — Nico Haase, Nov 25 '22 at 12:48

score 2 · Answer 1 · answered Nov 25 '22 at 11:56

Passing null to parameter #2 ($subject) of type string is deprecated

First of all, this warning only appears if you enable strict typing (which is a good thing, don't get me wrong):

declare(strict_types=1);

It makes more sense to avoid the check altogether:

if ($article->text !== null && preg_match($email, $article->text)) {
}

But, if that isn't feasible for whatever the reason, you can also default to empty string:

if (preg_match($email, $article->text ?? '')) {
}

On a side note, PHP has native email validation.

score 0 · Answer 2 · answered Nov 25 '22 at 13:03

It is actually not caused by PHP, but by the Joomla CMS. There are situations where $article->text has not been defined. Thanks to all who have steered mine in the right direction through their thoughts.

$email = '/[^@:="\'\s]*@[^@\s]*\.[a-z]+/iU';
if($article->text AND preg_match($email,$article->text) == true) {
  to something
}

How to check in PHP8 if a unknown variable (e.g. e-mail) is in a string?

2 Answers2