在两页中定义常量，在另一页中包含一个

Question

What will happen if a constant is defined on one page say index.php and then again defined on the other page say header.php and then header.php is included in index.php? This question was asked in an interview and I am wondering what the outcome would really be.

Answer 1

If you have used error_reporting(E_ALL); It will show you

Notice: Constant 'CONSTANT NAME' already defined in 'file name'.

Better you check before define new constant like:

if (!defined(CONSTANT)) { define ('CONSTANT', 'Constant Value'); }