If you intend on creating a lot of custom exceptions, you may find this code useful.  I've created an interface and an abstract exception class that ensures that all parts of the built-in Exception class are preserved in child classes.  It also properly pushes all information back to the parent constructor ensuring that nothing is lost.  This allows you to quickly create new exceptions on the fly.  It also overrides the default __toString method with a more thorough one.<?phpinterfaceIException{/* Protected methods inherited from Exception class */public functiongetMessage();// Exception messagepublic functiongetCode();// User-defined Exception codepublic functiongetFile();// Source filenamepublic functiongetLine();// Source linepublic functiongetTrace();// An array of the backtrace()public functiongetTraceAsString();// Formated string of trace        /* Overrideable methods inherited from Exception class */public function__toString();// formated string for displaypublic function__construct($message=null,$code=0);}abstract classCustomExceptionextendsExceptionimplementsIException{    protected$message='Unknown exception';// Exception messageprivate$string;// Unknownprotected$code=0;// User-defined exception codeprotected$file;// Source filename of exceptionprotected$line;// Source line of exceptionprivate$trace;// Unknownpublic function__construct($message=null,$code=0)    {        if (!$message) {            throw new$this('Unknown '.get_class($this));        }parent::__construct($message,$code);    }        public function__toString()    {        returnget_class($this) ." '{$this->message}' in{$this->file}({$this->line})\n"."{$this->getTraceAsString()}";    }}?>Now you can create new exceptions in one line:<?phpclassTestExceptionextendsCustomException{}?>Here's a test that shows that all information is properly preserved throughout the backtrace.<?phpfunctionexceptionTest(){    try {        throw newTestException();    }    catch (TestException $e) {        echo"Caught TestException ('{$e->getMessage()}')\n{$e}\n";    }    catch (Exception $e) {        echo"Caught Exception ('{$e->getMessage()}')\n{$e}\n";    }}echo'<pre>'.exceptionTest() .'</pre>';?>Here's a sample output:Caught TestException ('Unknown TestException')TestException 'Unknown TestException' in C:\xampp\htdocs\CustomException\CustomException.php(31)#0 C:\xampp\htdocs\CustomException\ExceptionTest.php(19): CustomException->__construct()#1 C:\xampp\htdocs\CustomException\ExceptionTest.php(43): exceptionTest()#2 {main}

Custom error handling on entire pages can avoid half rendered pages for the users:<?phpob_start();try {/*contains all page logic     and throws error if needed*/...} catch (Exception $e) {ob_end_clean();displayErrorPage($e->getMessage());}?>

Easy to understand `finally`.<?phptry {    try {        echo"before\n";1/0;        echo"after\n";    } finally {        echo"finally\n";    }} catch (\Throwable) {    echo"exception\n";}?># Print:beforefinallyexception

The "finally" block can change the exception that has been throw by the catch block.<?phptry{        try {                throw new\Exception("Hello");        } catch(\Exception $e) {                echo$e->getMessage()." catch in\n";                throw$e;        } finally {                echo$e->getMessage()." finally \n";                throw new\Exception("Bye");        }} catch (\Exception $e) {        echo$e->getMessage()." catch out\n";}?>The output is:Hello catch inHello finally Bye catch out

‘Normal execution (when no exception is thrown within the try block, *or when a catch matching the thrown exception’s class is not present*) will continue after that last catch block defined in sequence.’‘If an exception is not caught, a PHP Fatal Error will be issued with an “Uncaught Exception …” message, unless a handler has been defined with set_exception_handler().’These two sentences seem a bit contradicting about what happens ‘when a catch matching the thrown exception’s class is not present’ (and the second sentence is actually correct).

As noted elsewhere, throwing an exception from the `finally` block will replace a previously thrown exception. But the original exception is magically available from the new exception's `getPrevious()`.<?phptry {    try {        throw newRuntimeException('Exception A');    } finally {        throw newRuntimeException('Exception B');    }}catch (Throwable $exception) {    echo$exception->getMessage(),"\n";// 'previous' is magically available!echo$exception->getPrevious()->getMessage(),"\n";}?>Will print:Exception BException A

In case your E_WARNING type of errors aren't catchable with try/catch you can change them to another type of error like this:<?php     set_error_handler(function($errno,$errstr,$errfile,$errline){            if($errno===E_WARNING){// make it more serious than a warning so it can be caughttrigger_error($errstr,E_ERROR);                returntrue;            } else {// fallback to default php error handlerreturnfalse;            }    });    try {// code that might result in a E_WARNING} catch(Exception $e){// code to handle the E_WARNING (it's actually changed to E_ERROR at this point)} finally {restore_error_handler();    }?>

#3 is not a good example. inverse("0a") would not be caught since (bool) "0a" returns true, yet 1/"0a" casts the string to integer zero and attempts to perform the calculation.

Starting in PHP 7, the classes Exception and Error both implement the Throwable interface. This means, if you want to catch both Error instances and Exception instances, you should catch Throwable objects, like this:<?phptry {    throw newError("foobar");// or:    // throw new Exception( "foobar" );}catch (Throwable $e) {var_export($e);}?>

When using finally keep in mind that when a exit/die statement is used in the catch block it will NOT go through the finally block.<?phptry {    echo"try block<br />";    throw newException("test");} catch (Exception $ex) {    echo"catch block<br />";} finally {    echo"finally block<br />";}// try block// catch block// finally block?><?phptry {    echo"try block<br />";    throw newException("test");} catch (Exception $ex) {    echo"catch block<br />";    exit(1);} finally {    echo"finally block<br />";}// try block// catch block?>

<?php/** * You can catch exceptions thrown in a deep level function */functionemployee(){    throw new\Exception("I am just an employee !");}functionmanager(){employee();}functionboss(){    try {manager();    } catch (\Exception $e) {        echo$e->getMessage();    }}boss();// output: "I am just an employee !"

Contrary to the documentation it is possible in PHP 5.5 and higher use only try-finally blocks without any catch block.

the following is an example of a re-thrown exception and the using of getPrevious function:<?php$name="Name";//check if the name contains only letters, and does not contain the word nametry   {   try     {      if (preg_match('/[^a-z]/i',$name))        {           throw newException("$name contains character other than a-z A-Z");       }          if(strpos(strtolower($name),'name') !==FALSE)       {          throw newException("$name contains the word name");       }       echo"The Name is valid";     }   catch(Exception $e)     {     throw newException("insert name again",0,$e);     }   } catch (Exception $e)   {   if ($e->getPrevious())   {    echo"The Previous Exception is: ".$e->getPrevious()->getMessage()."<br/>";   }   echo"The Exception is: ".$e->getMessage()."<br/>";   }?>