.. _using-null-as-the-key-parameter-for-array_key_exists()-is-deprecated,-use-an-empty-string-instead:

Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead
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		Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead: ``null`` cannot be used as an array index anymore, since PHP 8.
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Description
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``null`` cannot be used as an array index anymore, since PHP 8.5. It is deprecated. As such, there is no point anymore to in passing such values to the first argument of array_key_exists(), and this is also deprecated.

Example
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.. code-block:: php

   <?php
   
   $array = [null => 1];
   var_dump(array_key_exists(null, $array));
   
   ?>

Solutions
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+ Use the coalesce operator ``??`` to turn the ``null`` into another value, such as empty string.
+ Replace the ``null`` value by the empty string.

Related Error Messages
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+ :ref:`using-null-as-an-array-offset-is-deprecated,-use-an-empty-string-instead`

Changed Behavior
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This error may appear following an evolution in behavior, in previous versions. See `NullAsArrayOffset <https://php-changed-behaviors.readthedocs.io/en/latest/behavior/NullAsArrayOffset.html>`_, `NullWithArrayKeyExists <https://php-changed-behaviors.readthedocs.io/en/latest/behavior/NullWithArrayKeyExists.html>`_.