PHP constants are name or identifier that can't be changed during the execution of the script. PHP constants can be defined by 2 ways:
PHP constants follow the same PHP variable rules. For example, it can be started with letter or underscore only.
Conventionally, PHP constants should be defined in uppercase letters.
PHP constant: define()
Let's see the syntax of define() function in PHP.
Let's see the example to define PHP constant using define().File: constant1.php
Hello JavaTpoint PHP
Hello JavaTpoint PHPHello JavaTpoint PHP
Hello JavaTpoint PHP Notice: Use of undefined constant message - assumed 'message' in C:\wamp\www\vconstant3.php on line 4 message
PHP constant: const keyword
The const keyword defines constants at compile time. It is a language construct not a function.
It is bit faster than define().
It is always case sensitive.File: constant4.php
Hello const by JavaTpoint PHP