PHP Constants

Table of Contents

• PHP Constants
  • PHP 1 Create a PHP Constant
    • Example 1
  • PHP 2 const Keyword
    • Example 2
  • PHP 3 Constant Arrays
    • Example 3
  • PHP 4 Constants are Global
    • Example 4
  • Document
  • Reference

PHP 1 Create a PHP Constant

<h2>php Constants-Create_a_PHP_Constant</h2>
<p>To create a constant, use the define() function.</p>

<?php
    // case-sensitive constant name
    define("GREETING", "Welcome to W3Schools.com!");
    echo GREETING;
?>

Example 1

Result View Example

PHP 2 const Keyword

<h2>php Constant-const_Keyword</h2>
<p>You can also create a constant by using the const keyword.</p>

<?php
    // Create a case-sensitive constant with the const keyword:
    const MYCAR = "Volvo";

    echo MYCAR;
?>

Example 2

Result View Example

PHP 3 Constant Arrays

<h2>Constant Arrays</h2>
<p>From PHP7, you can create an Array constant using the define() function.</p>

<?php
    define("cars", [
        "Alfa Romeo",
        "BMW",
        "Toyota"
    ]);
    echo cars[2];
?>

Example 3

Result View Example

PHP 4 Constants are Global

<h2>php Constants-Constants_are_Global</h2>
<p>Constants are automatically global and can be used across the entire script.</p>

<?php
// This example uses a constant inside a function, even if it is defined outside the function:
    
    define("GREETING", "Welcome to W3Schools.com!");
    
    function myTest() {
    echo GREETING;
    }

    myTest();
?>

Example 4

Result View Example

Document

Document in project

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Reference