Analysis of _php Examples of PHP exception handling

PHP has ordered two exception classes: Exception and Errorexception

Copy Code code 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
}

Copy Code code as follows:

Errorexception extends Exception {

/* Properties * *
protected int $severity;
/* Method * *

Public __construct ([string $message = "] [, int $code = 0 [, int $severity = 1 [, String $filename = __file__ [ , int $lineno = __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.

Copy Code code 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.

Copy Code code 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.

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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 keyword, you need not care about whether the exception overflow.

Can be compared as follows:

Copy Code code 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);
}
}