Catch keyword in php

 

 

 

 

 

 

 

 

 

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 keyword

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 bethrown (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().

finally keyword in php

In PHP 5.5 and later, a finally block may also be specified after or instead of catch blocks. Code within the finallyblock will always be executed after the try and catch blocks, regardless of whether an exception has been thrown, and before normal execution resumes.

<?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”;
?>

Above code will show

0.2
Caught exception: Division by zero.
Hello World

 

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”;
?>

 

 Nested Exception example  in php

<?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!"
 
 

The above example will output:

0.2
First finally.
Caught exception: Division by zero.
Second finally.
Hello World
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