PhpStorm warning PHP variable might not have been defined

Question

Consider:

<?php
  //  $smith = "";
  $submit ="button_a";

  if($submit == "button_a") {
      $smith = "button_a";
  }
    elseif($submit == "button_b"){
      $smith = "button_b";
  }
?>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
</head>

<body>
    <p>
        <?php echo($smith);  ?>
    </p>
</body>

</html>

PhpStorm provides a flag for each file: Red - Errors, Yellow - Warning, Green - OK.

The PHP code above the header will assign a value to $smith. In the body, I get a warning on $smith saying that it might be undefined. If I declare all of the variable at the top of the PHP code, ($smith = "";) it is happy (no warning).

Is there something that I should be doing to prevent these warnings?

I don't like the idea of attaching the comment to each one saying to not check it and I don't want to turn them all off.

This happens a lot when I include my db_login.php file which defines four or five variables. I have different db_login.php files for WAMP, MAMP, and the real hose.

Any thoughts?

I would thoroughly recommend tho always declaring/initialising a variable before any use... makes debugging so much easier. — Brian
– Brian, Commented Aug 1, 2012 at 8:52
... and not to use global variables for settings (e.g. db details etc -- static class for a help) -- if it's your own code, of course :) — LazyOne
– LazyOne, Commented Aug 1, 2012 at 13:17

Peter Mortensen · Accepted Answer · 2021-08-08 22:35:31Z

17

You can tell PhpStorm to ignore undefined variables reports if require on include statements are located in the same execution flow before the variable access.

You'll find it in 'Undefined variable' - Ignore 'include' and 'require' statements. It is enabled by default, so you should disable it.

Enter image description here

*Note: The setting is in menu File → Settings (Ctrl + Alt + S) → Project Settings → Inspections → PHP → Undefined → Undefined variable

edited Aug 8, 2021 at 22:35

Peter Mortensen

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answered Aug 1, 2012 at 1:28

Dreen

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3 Comments

bafromca Over a year ago

Where are these settings?

terenaa Over a year ago

File > Settings (Ctrl+Alt+S) > Project Settings > Inspections > PHP > Undefined > Undefined variable

tishma Over a year ago

Thanks Kobra. @Dreen: pls update the answer, as screenshot really lacks context.

Peter Mortensen · Accepted Answer · 2021-08-08 22:32:32Z

7

Yeah, there are two things you can do to get rid of this warning. What you said:

$smith = "";
if($submit == "button_a") {
    $smith = "button_a";
}
elseif($submit == "button_b"){
    $smith = "button_b";
}

Or check if it's set when you print it:

<?php
    if( isset( $smith)) {
        echo($smith);
    }
?>

However, this is just a warning, and it is letting you know that there is a condition that $smith won't be defined (when $submit isn't "button_a" and isn't "button_b"). If that condition were to occur, you would be printing $smith when it wasn't set, which could be a bug in your script.

edited Aug 8, 2021 at 22:32

Peter Mortensen

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answered Aug 1, 2012 at 1:23

nickb

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2 Comments

mkstlwtz Over a year ago

PHPSTORM is smarter than I had thought. If I change elseif to else so that all paths through the code assign a value, it is happy. What about my db_login include file that defines database, user, password, table, etc. Any way to make it "look into" the include file so that I don't have to predefine them all?

nickb Over a year ago

Because then there's no conditions that exist in which $smith wouldn't be defined. It's actually helpful (IMO), as it's telling you that a condition exists where you'd be accessing a variable that hasn't been defined. You'd only get this info from PHP if you executed the script with the "bug" conditions (i.e. where $submit isn't button_a or button_b). For your include file issues, see Dreen's answer below.

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