== Why is this an issue?

At root, ``++require++``, ``++require_once++``, ``++include++``, and ``++include_once++`` all perform the same task of including one file in another.
However, the way they perform that task differs, and they should not be used interchangeably.

* ``++require++`` includes a file but generates a fatal error if an error occurs in the process.

* ``++include++`` also includes a file, but generates only a warning if an error occurs.

Predictably, the difference between ``++require++`` and ``++require_once++`` is the same as the difference between ``++include++`` and ``++include_once++``.
The ``++_once++`` versions ensure that the specified file is only included once.

=== What is the potential impact?

Including the same file multiple times could have unpredictable results, the ``++_once++`` versions are preferred.
Additionally, as ``++include_once++`` generates only warnings, it should be used only when the file is being included conditionally, i.e. when all possible error conditions have been checked beforehand.

== How to fix it

Rewrite your code to only contain `require_once` and conditional `include_once` calls.

=== Code examples

==== Noncompliant code example

[source,php,diff-id=1,diff-type=noncompliant]
----
include 'code.php';  //Noncompliant; not a "_once" usage and not conditional
include $user.'_history.php'; // Noncompliant
require 'more_code.php';  // Noncompliant; not a "_once" usage
----

==== Compliant solution

[source,php,diff-id=1,diff-type=compliant]
----
require_once 'code.php';
if (is_member($user)) {
  include_once $user.'_history.php';
}
require_once 'more_code.php';
----

== Resources

=== Documentation

* https://www.php.net/manual/en/function.require-once.php[PHP Manual - require-once]
* https://www.php.net/manual/en/function.require.php[PHP Manual - require]
* https://www.php.net/manual/en/function.include-once.php[PHP Manual - include-once]
* https://www.php.net/manual/en/function.include.php[PHP Manual - include]

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== Implementation Specification

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=== Message

Replace "xxx" with "yyy".


'''

== Comments And Links

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=== on 19 May 2015, 15:51:55 Linda Martin wrote:
Reviewed

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