Illegal array key

Question

This function

function convert($size) {
  $unit = array(
    'B',
    'KByte',
    'MByte',
    'GByte',
  );
  return round($size / pow(1024, ($i = floor(log($size, 1024)))), 2) . ' ' . $unit[$i];
}

works but PHPStorm says

Illegal array key type on line 54

that means $unit[$i].

What's wrong with this function?

First guess - PHPStorm sees that floor returns a float, and using a float as an array key is usually a no-no. Be advised that some other functions, like array_key_exists, will actually produce a runtime error if you pass that $i as the key, based solely on its type. — user1233508
– user1233508, Commented Nov 16, 2013 at 14:41

Community · Accepted Answer · 2023-11-17 20:38:18Z

4

floor returns a float, not an integer. (Counter-intuitive, but true.) Floats are illegal keys in PHP arrays.

The code works fine, because floats are implicitly cast to integers when used as keys in an array, but I imagine that is why you are getting the notification in PHPStorm.

edited Nov 17, 2023 at 20:38

CommunityBot

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answered Nov 16, 2013 at 14:42

lonesomeday

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1 Comment

Ronny Linsener Over a year ago

I fixed it now with $unit[(int)$i] and the notification is gone.

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