Try Catch

During program execution an error can be thrown. Instead of ending the program an error can be caught and a certain code can be executed.

Error Handling

Syntax for handling error:

try { // code that may throw exception. } catch (ExceptionType exceptionName) { // handling the error }

Let's look at the following example:

<?php try { echo "Executing try block code.\n"; throw new Exception("My error message.\n"); } catch (Exception $ex) { echo "Catching an error:\n"; echo $ex->getMessage(); }

Output:

Executing try block code. Catching an error: My error message.

Since an error is thrown in the try block, the code from the catch block is called.

Classes and Error Handling

An error can be thrown when a validation fails in setter.

Example:

<?php class Person { private $name; private $age; public function setAge($ageValue) { if ($ageValue < 0) { throw new Exception("Age cannot be less than zero.\n"); } $this->age = $ageValue; } public function setName($nameValue) { $this->name = $nameValue; } public function __construct($usernameValue, $ageValue) { $this->setName($usernameValue); $this->setAge($ageValue); } } try { $personObj = new Person("Alex", -1); } catch (Exception $ex) { echo "Object creation failed:\n"; echo $ex->getMessage(); }

Output:

Object creation failed: Age cannot be less than zero.

At line 31 a negative number (-1) is passed for age of the person object. This causes an error to be throw (due to line 11).