Can I declare that a php function throws an exception?

Question

Can I declare a function in php that throws an exception? For example:

public function read($b, $off, $len) throws IOException 

Answer 1

You could throw a new exception from the body of the function. It's all described here

Example:

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

Answer 2

For a list of exceptions that come with the SPL: SPL Exceptions.

If you want to create your own exception:

From the PHP Exceptions page:

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.

So yes, it is possible to create your own exceptions. Just a bit of reading will help you achieve what you want.