How to check if a defined constant exists in PHP?

Question

So I\'m using a PHP framework called fuelphp, and I have this page that is an HTML file, so I can\'t use PHP in it. I have another file tha

Answer 1

First, these are not variables, but constants.

And you can check their existence by using the defined() function :

bool defined ( string $name )

Checks whether the given constant exists and is defined.