Просмотр исходного текста страницы 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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