Exception Handling - PHP Manual Notes

Exceptions generated in PHP code can be thrown by the throw statement and captured by the catch statement. Code that requires exception handling must be placed within the try code block, and each try must have at least one corresponding catch. When an exception is thrown, the code following the code block will not continue to execute. At this time, PHP will try to find the first matching catch. Of course, PHP allows throw exceptions to be thrown again within a catch code block. If an exception is not caught and handled accordingly using set_exception_handler(), PHP will generate a fatal error.

Here is an example of exception usage.

<code><?php
function inverse($x) {
    if(!$x) {
        throw new Exception(&#39;Division by zero.&#39;);
    } else {
        return 1 / $x;
    }
}
try {
    echo inverse(5) . &#39;<br>';
    echo inverse(0) . '<br>';
} catch(Exception $e) {
    echo 'Caught exception: ' . $e->getMessage() . '<br>';
}
echo 'hello';</code>

There is also an example of exception nesting.

<code><?php
class MyException extends Exception {}
class Test {
    public function testing() {
        try {
            try {
                throw new MyException(&#39;foo.&#39;);
            } catch(MyException $e) {
                throw $e;
            }
        } catch(Exception $e) {
            var_dump($e->getMessage());
        }
    }
}
$foo = new Test;
$foo->testing();</code>

Users can extend PHP's built-in exception handling classes with custom exception handling classes.

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