.. _structures-dontreadandwriteinoneexpression:

.. _don't-read-and-write-in-one-expression:

Don't Read And Write In One Expression
++++++++++++++++++++++++++++++++++++++

  Avoid giving value and using it at the same time, in one expression. This is an undefined behavior of PHP, and may change without warning.

One of those changes happens between PHP 7.2 and 7.3 :

.. code-block:: php
   
   <?php
   
   $arr = [1];
   $ref =& $arr[0];
   var_dump($arr[0] + ($arr[0] = 2));
   // PHP 7.2: int(4)
   // PHP 7.3: int(3)
   
   ?>

See also `UPGRADING 7.3 <https://github.com/php/php-src/blob/PHP-7.3/UPGRADING#L83-L95>`_.


Suggestions
___________

* Split the expression in two separate expressions




Specs
_____

+--------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Short name   | Structures/DontReadAndWriteInOneExpression                                                                                                                                                                                                             |
+--------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Rulesets     | :ref:`All <ruleset-All>`, :ref:`Analyze <ruleset-Analyze>`, :ref:`CE <ruleset-CE>`, :ref:`Changed Behavior <ruleset-Changed-Behavior>`, :ref:`CompatibilityPHP73 <ruleset-CompatibilityPHP73>`, :ref:`CompatibilityPHP74 <ruleset-CompatibilityPHP74>` |
+--------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Exakat since | 1.4.9                                                                                                                                                                                                                                                  |
+--------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| PHP Version  | All                                                                                                                                                                                                                                                    |
+--------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Severity     | Critical                                                                                                                                                                                                                                               |
+--------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Time To Fix  | Quick (30 mins)                                                                                                                                                                                                                                        |
+--------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Precision    | High                                                                                                                                                                                                                                                   |
+--------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Available in | `Entreprise Edition <https://www.exakat.io/entreprise-edition>`_, `Community Edition <https://www.exakat.io/community-edition>`_, `Exakat Cloud <https://www.exakat.io/exakat-cloud/>`_                                                                |
+--------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+