Exceptions
Table of Contents
- Extending Exceptions
PHP 5 has an exception model similar to that of other programming languages. An exception can be thrown, and caught ("catched") within PHP. Code may be surrounded in a try block, to facilitate the catching of potential exceptions. Each try must have at least one corresponding catch or finally block.
The thrown object must be an instance of the Exception class or a subclass of Exception. Trying to throw an object that is not will result in a PHP Fatal Error.
catch
Multiple catch blocks can be used to catch different classes of exceptions. Normal execution (when no exception is thrown within the try block) will continue after that last catch block defined in sequence. Exceptions can be thrown (or re-thrown) within a catch block.
When an exception is thrown, code following the statement will not be executed, and PHP will attempt to find the first matching catch block. 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().
In PHP 7.1 and later, a catch block may specify multiple exceptions using the pipe (|) character. This is useful for when different exceptions from different class hierarchies are handled the same.
finally
In PHP 5.5 and later, a finally block may also be specified after or instead of catch blocks. Code within the finally block will always be executed after the try and catch blocks, regardless of whether an exception has been thrown, and before normal execution resumes.
Notes
Note: Internal PHP functions mainly use Error reporting, only modern Object oriented extensions use exceptions. However, errors can be simply translated to exceptions with ErrorException.
Tip
The Standard PHP Library (SPL) provides a good number of built-in exceptions.
Examples
Example #3 Throwing an Exception
<?php
function?inverse($x)?{
????if?(!$x)?{
????????throw?new?Exception('Division?by?zero.');
????}
????return?1/$x;
}
try?{
????echo?inverse(5)?.?"\n";
????echo?inverse(0)?.?"\n";
}?catch?(Exception?$e)?{
????echo?'Caught?exception:?',??$e->getMessage(),?"\n";
}
//?Continue?execution
echo?"Hello?World\n";
?>The above example will output:
0.2
Caught exception: Division by zero.
Hello WorldExample #4 Exception handling with a finally block
<?php
function?inverse($x)?{
????if?(!$x)?{
????????throw?new?Exception('Division?by?zero.');
????}
????return?1/$x;
}
try?{
????echo?inverse(5)?.?"\n";
}?catch?(Exception?$e)?{
????echo?'Caught?exception:?',??$e->getMessage(),?"\n";
}?finally?{
????echo?"First?finally.\n";
}
try?{
????echo?inverse(0)?.?"\n";
}?catch?(Exception?$e)?{
????echo?'Caught?exception:?',??$e->getMessage(),?"\n";
}?finally?{
????echo?"Second?finally.\n";
}
//?Continue?execution
echo?"Hello?World\n";
?>The above example will output:
0.2
First finally.
Caught exception: Division by zero.
Second finally.
Hello WorldExample #5 Nested Exception
<?php
class?MyException?extends?Exception?{?}
class?Test?{
????public?function?testing()?{
????????try?{
????????????try?{
????????????????throw?new?MyException('foo!');
????????????}?catch?(MyException?$e)?{
????????????????//?rethrow?it
????????????????throw?$e;
????????????}
????????}?catch?(Exception?$e)?{
????????????var_dump($e->getMessage());
????????}
????}
}
$foo?=?new?Test;
$foo->testing();
?>The above example will output:
string(4) "foo!"Example #6 Multi catch exception handling
<?php
class?MyException?extends?Exception?{?}
class?MyOtherException?extends?Exception?{?}
class?Test?{
????public?function?testing()?{
????????try?{
????????????throw?new?MyException();
????????}?catch?(MyException?|?MyOtherException?$e)?{
????????????var_dump(get_class($e));
????????}
????}
}
$foo?=?new?Test;
$foo->testing();
?>The above example will output:
string(11) "MyException"← Errors in PHP 7
Extending Exceptions →
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