PHP: Global variable for all pages

I need a constant that can be called from every php page. So, for example, I declare this constant somewhere, $APP_VERSION = "5.5".

Then I would like to call this variable from any pages. how开发者_Python百科 to do this?

define('APP_VERSION', '5.5');

You can put that in the file that would be included into your pages. I'n that way you'd access it by APP_VERSION

echo APP_VERSION; //outputs 5.5

You can define constants using define:

define('APP_VERSION', '5.5');

Then, in other files:

echo APP_VERSION; // outputs '5.5'

http://php.net/manual/en/function.define.php

You could define a file (for example costant.php) which will contains all your constants and then you have to use include to be able to retrieve them in every script.