array_key_exists error baffling

Question

This is quite possibly NOT something that can be reproduced through a copy & paste. The issue I am having here is that array_key_exists simply is not working.

I have printed my code to the page; it is definitely of type array, not that that is required. The array key exists; I have cast between both string & integer and it is coming back not found.

Now, where it becomes most puzzling is that I have iterated between

$presets    = $this->presets->$name;
echo gettype($version).'<br>';
foreach ( $presets as $key=>$test ) {
    if ( $key===$version ) echo 'string found1<br>';
    elseif ( $key==$version ) echo 'string found2<br>';
}
if ( !array_key_exists($version,$presets) )
    echo 'array_key_exists string fail.<br>';

$version = intval($version);
echo gettype($version).'<br>';
foreach ( $presets as $key=>$test ) {
    if ( $key===$version ) echo 'int found1<br>';
    elseif ( $key==$version ) echo 'int found2<br>';
}
if ( !array_key_exists($version,$presets) )
    echo 'array_key_exists int fail.<br>';

Output:

string
string found1
array_key_exists string fail.
integer
int found2
array_key_exists int fail.

The output is absolutely strange because in both the int & string searches, the key matches. In fact, in the string search, it outputs "string found1", meaning that it === a key within the array. So, then, why is array_key_exists ALWAYS producing FALSE?

The variable $presets is some array whose indices are created using preg_match regex codes to parse the indices. That is the only added mystery I can come up with, though a manual comparison has proved that an === value was discovered, and therefore none of this should matter. array_key_exists should return TRUE

  Array
  (
      [100] => stdClass Object
          ()
  )

I can't reproduce this. But I also can't create an array whose key is a numeric string. Whenever I try to set the key to a string like `"100"`, it becomes the integer `100`. And your `var_dump()` shows a numeric key as well. — Barmar, Aug 29 '18 at 22:14
"_$presets is some array whose indices are created_...". Is it possible that presets is an object that is traversible? What are the outputs of `gettype($presets);`? — jh1711, Aug 29 '18 at 22:16
Reproducible when `$presets` is an `stdClass`: `php -r '$p = (object)["100" => new stdClass]; var_dump(array_key_exists("100", $p), array_key_exists(100, $p));'` Output: `bool(false), bool(false)` — weirdan, Aug 29 '18 at 22:36
@Barmar Maybe like this? https://stackoverflow.com/a/35180513/2734189 — Don't Panic, Aug 29 '18 at 22:48
@Don'tPanic Interesting. But that doesn't seem to be what's going on here, since the `var_dump()` shows an integer key. But his `foreach()` loops indicate that it's a string key. Something is not right. — Barmar, Aug 29 '18 at 22:50
the array listed is the dump of $presets. I am going to look into the answer below about "numeric-strings" being a thing in <7.2 ... hmm. Thank you this far! — Antago, Aug 30 '18 at 04:11
EDIT: I have discovered something that appears to be sweeped under the rug and I don't know the solution necessarily just yet. This is apparently a fatal PHP error albeit apparently only *briefly* encountered. `get_object_vars` was used to convert my `object` to an `array`, and according to a bug report in PHP 7.1, `array_key_exists` won't work with numeric keys from said `get_object_vars` conversion. — Antago, Aug 30 '18 at 04:29

Don't Panic · Answer 1 · 2018-08-29T23:12:14.107

Based on the results you got from $key==$version and $key===$version, we know that the key is a numeric string. So it appears you are using a version of PHP < 7.2.

In those versions, you can't reference a numeric string array key, and array_key_exists will return false whether you give the key in numeric or string form. This confusing behavior was improved with PHP 7.2.

Here's a demo illustrating this, based on the example from this answer.

array_key_exists error baffling

1 Answers1