Language Reference / Exceptions

Catch

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().

finally

In PHP 5.5 and later, a finally block may also be specified(指定) 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(回復).

Examples: Throwing an Exception

<?php
function inverse($x) {
    if (!$x) {
        throw new Exception('Division by zero.');
    }
    return 1/$x;
}

try {
    echo inverse(5) . "\n"; // 0.2
    echo inverse(0) . "\n"; // Caught exception: Division by zero
} catch (Exception $e) {
    echo 'Caught exception: ',  $e->getMessage(), "\n";
}

// Continue execution
echo "Hello World\n"; // Hellow World
?>

Examples: 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"; // 0.2
} catch (Exception $e) {
    echo 'Caught exception: ',  $e->getMessage(), "\n";
} finally {
    echo "First finally.\n"; // First finally.
}

try {
    echo inverse(0) . "\n"; // Caught exception: Division by zero.
} catch (Exception $e) {
    echo 'Caught exception: ',  $e->getMessage(), "\n";
} finally {
    echo "Second finally.\n"; // Second finally.
}

// Continue execution
echo "Hello World\n"; // Hello World
?>

Examples: Nested Exception

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(); // string(4) "foo!"

Examples: Multi catch exception handling - PHP 7.1 以上

<?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(); //string(11) "MyException"
?>

Note:

1. Internal PHP functions mainly use Error reporting, only modern Object oriented extensions use exceptions. However, errors can be simply translated to exceptions with ErrorException.