Programming PHP, 3rd Edition

Error Handling

Error handling is an important part of any real-world application. PHP provides a number of mechanisms that you can use to handle errors, both during the development process and once your application is in a production environment.

Error Reporting

Normally, when an error occurs in a PHP script, the error message is inserted into the script’s output. If the error is fatal, the script execution stops.

There are three levels of conditions: notices, warnings, and errors. A notice is a condition encountered while executing a script that might be an error, but could also be encountered during normal execution (e.g., trying to access a variable that has not been set). A warning indicates a nonfatal error condition; typically, warnings are displayed when calling a function with invalid arguments. Scripts will continue executing after issuing a warning. An error indicates a fatal condition from which the script cannot recover. A parse error is a specific kind of error that occurs when a script is syntactically incorrect. All errors except parse errors are runtime errors.

It’s recommended that you treat all notices, warnings, and errors as if they were errors; this helps prevent mistakes such as using variables before they have legitimate values, and so on.

By default, all conditions except runtime notices are caught and displayed to the user. You can change this behavior globally in your php.ini file with the error_reporting option. You can also locally change the error-reporting ...