phpconstantsdefinedredefine

I can redefine constant in PHP without getting an error

As I know we can't redefine a constant in PHP. So if I do:

define("DEVELOPMENT", true);

theoretical I can not redefine it using:

define("DEVELOPMENT", false); (or) const DEVELOPMENT = false;

The problem is PHP let me do that. It lets me redefining a constant without throwing any error. Display error is on (I got any other error):

ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL & ~E_WARNING & ~E_NOTICE & ~E_STRICT & ~E_DEPRECATED);

What to do so constants can't be redefined and to get error if I try?

My PHP version is 7.2.17

Solution

  • To report all php error

    error_reporting(E_ALL);

    To report all php errors except notices

    error_reporting(E_ALL & ~E_NOTICE);

    And in your case, you are redefining a constant that has been already defined show PHP throws a notice. By using

    error_reporting(E_ALL & ~E_WARNING & ~E_NOTICE & ~E_STRICT & ~E_DEPRECATED);

    You are telling PHP not to report any kind of notices or warnings. You should remove them.
    To get all warning and notices use

    error_reporting(E_ALL);

    Fore more information refer to the official doc, and have a look on examples.