PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

564 Chapter 26 Debugging
By default, when a fatal error occurs, PHP outputs
Error Type: error message in path/file.php
on line lineNumber
and stops executing the script. For nonfatal errors, the same text is output, but execution
is allowed to continue.
This HTML output makes the error stand out but looks poor.The style of the error
message is unlikely to fit the rest of the site’s look. It might also result in some users seeing
no output at all if the page’s content is being displayed within a table and their
browser is fussy about valid HTML. HTML that opens but does not close table elements,
such as
Error Type: error message in path/file.php
on line lineNumber
is rendered as a blank screen by some browsers.
You do not have to keep PHP’s default error handling behavior or even use the same
settings for all files.To change the error reporting level for the current script, you can call
the function error_reporting().
Passing an error report constant, or a combination of them, sets the level in the same
way that the similar directive in php.ini does.The function returns the previous error
reporting level. A common way to use the function is like this:
// turn off error reporting
$old_level = error_reporting(0);
// here, put code that will generate warnings
// turn error reporting back on
error_reporting($old_level);
This code snippet turns off error reporting, allowing you to execute some code that is
likely to generate warnings that you do not want to see.
Turning off error reporting permanently is a bad idea because it makes finding your
coding errors and fixing them more difficult.
Triggering Your Own Errors
The function trigger_error() can be used to trigger your own errors. Errors created
in this way are handled in the same way as regular PHP errors.
The function requires an error message and can optionally be given an error type.
The error type needs to be one of E_USER_ERROR, E_USER_WARNING, or E_USER_NOTICE.
If you do not specify a type, the default is E_USER_NOTICE.