Can you undefine or change a constant in PHP?

Question

Can you undefine or change a constant in PHP?

Answer 1

The other posters are correct - you can't do this. But perhaps you can move your definition to the point where you know what the best value for the constant would be.

Perhaps you're defining constants in a big list:

define('STRING1','Foo');
define('STRING2', 'Bar');
define('STRING3', 'Baz'); 

and you want to change the value of STRING2 once you discover a condition. One way would be to defer the definition until you know the correct setting.

define('STRING1','Foo');
// define('STRING2', 'Bar');  -- wait until initialization
define('STRING3', 'Baz');

...


if (condition) { 
   define('STRING2', 'Bar type 2');
} else {
   define('STRING2', 'Bar type 1');
}

The logic setting STRING2 could even be in a different file, later on in your processing.