Question

Imagine I have this constant in PHP:

define('APP_PATH', str_replace('//', '/', str_replace('\\', '/', dirname(__FILE__) . '/')));

When I use APP_PATH in my application, does PHP execute the code (dirname, and the two str_replace on __FILE__) each time or PHP execute the code once and store the result in APP_PATH ? I hope I’m clear enough 🙂

This question applies to PHP 5.1.0+.

Answer 1

It should be done once, at the time it was defined.

UPDATED
For documentation: define() – constants

From the documentation:

A constant is an identifier (name) for a simple value. As the name suggests, that value cannot change during the execution of the script (except for magic constants, which aren’t actually constants). A constant is case-sensitive by default. By convention, constant identifiers are always uppercase.

If you want more information on constants go ahead and read the documentation, it is explained pretty well there and probably has usage examples.