require_once
require_once
(PHP 4, PHP 5, PHP 7)
The require_once statement is identical to require except PHP will check if the file has already been included, and if so, not include (require) it again.
See the include_once documentation for information about the _once behaviour, and how it differs from its non _once siblings.
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Licensed under the Creative Commons Attribution License v3.0 or later.
https://secure.php.net/manual/en/function.require-once.php
