How can the order of includes and variable definitions impact the availability of constant variables in PHP?

The order of includes and variable definitions in PHP can impact the availability of constant variables because constants are defined at compile time and must be defined before they are used. To ensure constant variables are available throughout the code, it is best practice to define constants at the beginning of the script, before any other code that may rely on them. 

<?php
// Define constant variable
define('MY_CONSTANT', 'Hello, World!');

// Include other files or define variables that rely on the constant
include 'my_file.php';

// Use the constant variable
echo MY_CONSTANT;
?>

Keywords

includes variable definitions constant variables availability PHP

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