Describes the process and principle of the PHP exception mechanism

What is the principle of the PHP exception mechanism? What is the ZEND_HANDLE_EXCEPTION at the end of every oparray that can be executed independently in PHP? Let's start with a question. For the code, onError is executed, but onException is not executed. why? & Lt ;? Php & nbsp; function & nbsp; onError ($ errCo what is the principle of the PHP exception mechanism? What is the ZEND_HANDLE_EXCEPTION at the end of each op array that can be executed independently in PHP? Let's start with a question.

For the code, onError is executed, but onException is not executed. why?

 

  

   
  
Function onError ($ errCode, $ errMesg, $ errFile, $ errLine ){
  
Echo "Error Occurred \ n ";
  
Throw new Exception ($ errMesg );
  
}
  
Function onException ($ e ){
  
Echo $ e-> getMessage ();
  
}
  
Set_error_handler ("onError ");
  
Set_exception_handler ("onException ");
  
/* I will never name the file with my name, so this file does not exist */
  
Require ("laruence. php ");
 

Running result:

 

  
Error Occurred　   
  
PHP Fatal error: main(): Failed opening required 'laruence.php　
 

First, we need to know that when Require contains a problem that cannot be found, two errors will be thrown before and after:

1. WARNING: thrown when PHP tries to open this file.

2. E_COMPILE_ERROR: it is thrown after the function of opening the file from PHP fails to return.

As we know, set_error_handler cannot catch the E_COMPILE_ERROR error. Therefore, in onError, only the first WARNING error can be caught, but the exception thrown in onError is not caught by the default exception_handler? Let's talk about PHP.

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