Custom php error handling and php exception handling

To handle php exceptions, you must first know the php error level. let's take a look at the following: the value constant describes the 2E_WARNING non-fatal run-time error. Do not pause script execution. 8E_NOTICE

To handle php exceptions, you must first know the php error level, and look at the following:

Value	Constant	Description
2	E_WARNING	Non-fatal run-time error. Do not pause script execution.
8	E_NOTICE	Run-time notification. An error may occur when the script runs normally.
256	E_USER_ERROR	Fatal user-generated error. This is similar to the E_ERROR set by the programmer using the PHP function trigger_error.
512	E_USER_WARNING	Non-fatal user-generated warning. This is similar to the E_WARNING set by the programmer using the PHP function trigger_error.
1024	E_USER_NOTICE	User-generated notifications. This is similar to the E_NOTICE set by the programmer using the PHP function trigger_error.
4096	E_RECOVERABLE_ERROR	Possible fatal errors. Similar to E_ERROR, but can be captured by a user-defined handler. (See set_error_handler ())
8191	E_ALL	All errors and warnings except level E_STRICT. (In PHP 6.0, E_STRICT is part of E_ALL)

In general, we use if... else ..., when exit () and die () are used to handle errors, there are many limitations. how can we customize our processing mechanism?

1. Custom error functions

2. Custom error triggering mechanism

 80) {trigger_error ("error", E_USER_NOTICE) ;}?>

3. php exception handling:

(1) When an exception is thrown, the subsequent code will not be executed, but will jump directly to catch and directly execute the content in catch. if The exception is not caught, if set_exception_handler () is not used, a fatal error will occur.

Let's look at an example in the manual:

 1) {throw new Exception ("Value must be 1 or below");} return true;} // trigger an Exception in the "try" code block try {checkNum (2 ); echo 'If you see this, the number is 1 or below';} catch (Exception $ e) {echo 'message :'. $ e-> getMessage () ;}?>

Example of using set_exception_handler:

 ". $ E-> getMessage () ;}// modify the default exception processor set_exception_handler ("myException"); function func ($ num) {if ($ num> 100) {throw new Exception ("Your input value is too large! (Www.phpddt.com) ");} else {echo" OK ";} func (120);?>

Example of creating a custom Exception class:

 GetLine (). 'in'. $ this-> getFile ().':'. $ This-> getMessage ().''; Return $ errorMsg; }}$ num = 120; try {if ($ num> 100) {throw new myException ("The number is too large ");}} catch (myException $ e) {echo $ e-> errorMessage () ;}?>

Of course, multiple exceptions can also be captured:

 GetLine (). 'in'. $ this-> getFile ().':'. $ This-> getMessage ().''; Return $ errorMsg; }}$ num = 120; try {if ($ num> 100) {throw new myException ("The number is too large ");}} catch (myException $ e) {echo $ e-> errorMessage ();} catch (Exception $ e) {echo $ e-> getMessage () ;}?>