Analysis of exception Handling in PHP

This article mainly introduces the analysis of the PHP exception handling, this article focuses on how to catch exceptions, and give examples of code operations, the need for friends can refer to the

PHP has ordered two exception classes: Exception and Errorexception

The code is as follows:

Exception {

/* Properties * *

protected string $message; Exception message Contents

protected int $code; Exception code number

protected string $file; Name of the exception thrown

protected int $line; The line number that throws the exception in the file

/* Method * *

Public __construct ([string $message = "" [, int $code = 0 [, Exception $previous = null]])

Final public string getMessage (void)//exception thrown information

Final public Exception getprevious (void)//Previous exception

Final public int getcode (void)//exception code, which is user-defined

Final public string getFile (void)//unexpected file path strength

Final public int getline (void)//The row in which the exception occurred

Final public array gettrace (void)//exception tracking information (array)

Final public string gettraceasstring (void)//Exception tracking information (string)

public string __tostring (void)//To call the return value of a child function when an exception object is used directly as a string

The final private void __clone (void)//is called when the exception object is cloned

}

The code is as follows:

Errorexception extends Exception {

/* Properties * *

protected int $severity;

/* Method * *

Public __construct ([string $message = "] [, int $code = 0 [, int $severity = 1 [, String $filename = __file__ [, int $li Neno = __line__ [, Exception $previous = NULL]]]]

Final public int getseverity (void)

/* Inheritance Method * *

Final public string exception::getmessage (void)

Final public Exception exception::getprevious (void)

Final public int exception::getcode (void)

Final public string exception::getfile (void)

Final public int exception::getline (void)

Final public array exception::gettrace (void)

Final public string exception::gettraceasstring (void)

public string exception::__tostring (void)

Final private void exception::__clone (void)

}

So how do I catch an exception?

(1) PHP can be try...catch ... To catch an exception, the code for exception handling must be within the try code block.

The code is as follows:

try {

throw new Exception (' Exception Test 1 ', 1001);

catch (Exception $e) {

echo $e->getmessage (). ' -'. $e->getcode ();

}

(2) The user can customize the exception handling function [Set_exception_handler] for exceptions that are not captured with Try/catch.

The code is as follows:

function Exception_handler ($e) {

echo "uncaught exception:", $e-> getMessage (), "n";

}

Set_exception_handler (' Exception_handler ');

throw new Exception (' uncaught Exception ');

echo "This line will not be carried out";

You can see that using the Ser_exception_handler callback function to handle exceptions, subsequent code will not continue to execute, but Try-catch can.

(3) PHP can catch different types of exceptions with multiple catch, and allow the exception to be thrown again within the catch code block.

The code is as follows:

Please extend the exception class according to the actual

Class MyException extends Exception {

Public function __construct ($message = ' ", $code = 0) {

}

Public Function MyFunction () {

Echo ' Just for test ';

}

}

try {

throw new MyException (' an error ');

catch (MyException $e) {

echo $e->myfunction ();

catch (Exception $e) {

echo $e->getmessage ();

}

(4) PHP5.5 has supported finally keywords, and you don't have to worry about whether the exception is overflowing.

Can be compared as follows:

The code is as follows:

function dosomething () {

$resource = Createresource ();

try {

$result = Useresource ($resource);

catch (Exception $e) {

Releaseresource ($resource);

Log ($e->getmessage ());

Exit ();

}

Releaseresource ($resource);

return $result;

}

After using finally

function DoSomething2 () {

$resource = Createresource ();

try {

$result = Useresource ($resource);

return $result;

catch (Exception $e) {

Log ($e->getmessage ());

Exit ();

finally {

Releaseresource ($resource);

}

}