Include and Require

Include Once Calculation

include_once can load a calculation helper exactly once.

shared calculation A helper file can use a value from the main file and prepare a scalar result.

Include Once Calculation

side
require_once_function.php
Replay: real traced execution (multi-file project)
<?php
$side = 4;
include_once __DIR__ . "/area_helper.inc";
include_once __DIR__ . "/area_helper.inc";

echo "side=" . $side . "\n";
echo "area=" . $area . "\n";

<?php
$side = 3;
include_once __DIR__ . "/area_helper.inc";
include_once __DIR__ . "/area_helper.inc";

echo "side=" . $side . "\n";
echo "area=" . $area . "\n";

<?php
$side = 8;
include_once __DIR__ . "/area_helper.inc";
include_once __DIR__ . "/area_helper.inc";

echo "side=" . $side . "\n";
echo "area=" . $area . "\n";

  1. $side ← 4

    1<?php2$side→ 4 = 4; //@side=3, 83include_once __DIR__ . "/area_helper.inc";4include_once __DIR__ . "/area_helper.inc";56echo "side=" . $side4 . "\n";7echo "area=" . $areaNULL . "\n";
    outputside=4
area=

  1. $side ← 3

    1<?php2$side→ 3 = 3;3include_once __DIR__ . "/area_helper.inc";4include_once __DIR__ . "/area_helper.inc";56echo "side=" . $side3 . "\n";7echo "area=" . $areaNULL . "\n";
    outputside=3
area=

  1. $side ← 8

    1<?php2$side→ 8 = 8;3include_once __DIR__ . "/area_helper.inc";4include_once __DIR__ . "/area_helper.inc";56echo "side=" . $side8 . "\n";7echo "area=" . $areaNULL . "\n";
    outputside=8
area=