PHP/Utility Function/include once

include_once and require_once will only include a file once

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//bar.php:

   <?php
           print "In bar\n";
   ?>

//index.php

   <?php
           include_once "bar.php";
           include_once "BAR.php";
           include_once "Bar.php";
   ?>
 
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include_once() function verifies whether or not the file has already been included.

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If it has been included, include_once() will not execute. Otherwise, it will include the file as necessary. Its syntax follows: include_once (file insertion_file)

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Using include_once to include a file

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A sample include file called add.php <?php function add( $x, $y ){

 return $x + $y;

} ?>

<?php include_once("add.php"); include_once("add.php"); echo add(2, 2); ?>

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