ZEND PHP 5 Certification STUDY GUIDE

34 ” PHP Basics
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Error reporting can also be changed dynamically from within a script by calling the
error_reporting() function.
The display_errors and log_errors directives can be used to determine how errors
are reported. If display_errors is turned on, errors are outputted to the script’s
output; generally speaking, this is not desirable in a production environment, as everyone
will be able to see your scripts’ errors. Under those circumstances, you will
instead want to turn on log_errors, which causes errors to be written to your web
server’s error log.
Handling Errors
Your scripts should always be able to recover from a trappable error—even if it’s
just to advise the user that an error occurred and notify support staff of the same
fact. This way, your script won’t simply capitulate when something unexpected
occurs—resulting in better communication with your customers and the possible
avoidance of some major problems.
Luckily, error handling is very easy. Your scripts can declare a catch-all
function that is called by PHP when an error condition occurs by calling the
set_error_handler() function:
$oldErrorHandler = ’’;
function myErrorHandler ($errNo, $errStr, $errFile, $errLine, $errContext) {
global $oldErrorHandler;
logToFile("Error $errStr in $errFile at line $errLine");
// Call the old error handler
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if ($oldErrorHandler) {
$oldErrorHandler ($errNo, $errStr, $errFile, $errLine, $errContext);
}
}
$oldErrorHandler = set_error_handler (’myErrorHandler’);