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Constants

 Constants in PHP are used to store values that do not change during the execution of a script. Unlike variables, once a constant is defined, its value cannot be modified or undefined. Constants are useful for storing configuration settings, fixed values, or any data that should remain the same throughout your application.

Defining Constants

You can define constants using the define() function or the const keyword.

Using define()

<?php
define("SITE_NAME", "My Web Blog");
echo SITE_NAME;
?>

Using const

<?php
const PI = 3.14159;
echo PI;
?>

Characteristics of Constants

·         Constant names are case-sensitive by default.

·         They do not start with a $ sign.

·         They can store scalar values like integers, strings, floats, and booleans.

·         They are globally accessible anywhere in the script.

Example with Constants

<?php
define("MAX_USERS", 100);
 
echo "The maximum number of users is: " . MAX_USERS;
 
const VERSION = "1.0.0";
echo "\nCurrent version: " . VERSION;
?>

Output:

The maximum number of users is: 100
Current version: 1.0.0

 

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