php三元运算符解释

Question

I am confused. I had set up the following code in my index.php to auto switch between xampp and server database config files:

define('ENVIRONMENT', isset($_SERVER['SERVER_NAME'])=='my_domain_name.com' ? 'production' : 'development');

    echo 'SERVER_NAME  '.$_SERVER['SERVER_NAME']; // getting localhost
    echo 'env '.ENVIRONMENT; // getting production.

In Xampp locally, I thought this would result in the ENVIRONMENT constant set to 'development' with $_SERVER['SERVER_NAME']=localhost. Would someone mind explaining what I'm doing wrong here?

Answer 1

define('ENVIRONMENT', isset($_SERVER['SERVER_NAME'])=='my_domain_name.com' ? 'production' : 'development');

Here you're comparing the result of isset() to 'my_domain_name.com'; you're comparing a boolean to a string.

What you want is to check "is $_SERVER['SERVER_NAME'] set AND is $_SERVER['SERVER_NAME'] equal to my_domain_name.com?", as follows:

define('ENVIRONMENT', (isset($_SERVER['SERVER_NAME']) && $_SERVER['SERVER_NAME'] == 'my_domain_name.com') ? 'production' : 'development');

(Or... just remove the isset() entirely.)