What Is An Constants In PHP Language Tutorial?

Hi guys,

Today i will explained What is Constants In PHP and how to use in php language. This example is so easy to use in php.

Constants is a one type variables except that once they are defined they cannot be changed or undefined. A constant is an identifier (name) for a simple value. The value cannot be changed during the script. A valid constant name starts with a letter or underscore (no $ sign before the constant name).

So let's start to the example.

Syntax

define(name, value, case-insensitive)
Parameters
-name: Specifies the name of the constant
-value: Specifies the value of the constant
-case-insensitive: Specifies whether the constant name should be case-insensitive. Default is false

Create A Constant with A Case-sensitive Name:

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

Output

Welcome to Nicesnippets.com!

Create A Constant With A Case-insensitive Name:

<?php
// case-insensitive constant name
define("GREETING", "Welcome to Nicesnippets.com!", true);
echo greeting;
?> 

Output

Welcome to Nicesnippets.com!

PHP Constant Arrays

In PHP7, you can create an Array constant using the define() function.

Create an Array constant:

<?php
define("cars", [
  "Alfa Romeo",
  "BMW",
  "Toyota"
]);
echo cars[0];
?> 

Output

Alfa Romeo

Constants are Global

Constants are automatically global and can be used across the entire script.

This example uses a constant inside a function, even if it is defined outside the function:

<?php
define("GREETING", "Welcome to Nicesnippets.com!");
  function myTest() {
    echo GREETING;
  }
myTest();
?> 

Output

Welcome to Nicesnippets.com!

Now you can check your own.

I hope it can help you...