Why suppress PHP errors?

问题:

I was wondering why you would “suppress” a PHP error. I obviously see the difference in the extra warning line that the error produces, but is it good to suppress it?

 Access denied for user 'user'@'localhost' (using password: YES) 

vs

Warning: mysql_connect() [function.mysql-connect]: Access denied for user 'user'@'localhost'       (using password: YES) in (deleted) on line 8
Access denied for user 'user'@'localhost' (using password: YES)

If so, should I get into the habit of typing @ at the start of my MySQL queries in my PHP programs?

回答1:

You should positively NOT get into the habit of suppressing errors. The errors are there for a reason. Instead, handle them properly and defensively in your code, and keep refining your code until the errors are gone.

You should do things like:

$conn = mysql_connect($host, $user, $pass);

// Always test to see if your action/connection/whatever was successful
if (!$conn) {
  // something went wrong.  handle the error
  // Display a message for the user, write a message to `error_log()`, whatever's appropriate
}
else mysql_select_db($dbname);

On a production system, you should never display errors, since it risks giving up details of your code and database. Instead, turn display_errors off in php.ini, or at runtime:

// In development and production, make sure all errors are reported
error_reporting(E_ALL & E_STRICT);

// In development show all errors on screen so you handle them as they occur
ini_set('display_errors', 1);

// In production turn them off
ini_set('display_errors', 0);

In fact, error suppression with @ is the second most voted for PHP bad practice in this classic question.