Exception Handling

Exception handling is carried out by the use of the keywords throw, trycatch.

 

An exception can be thrown and caught (catched).

 

  • Code may be surrounded in a try block, to facilitate the catching of potential exceptions
  • Each try must have at least one corresponding catch block
  • Multiple catch blocks can be used to catch different classes of exceptions
  • Normal execution (when no exception is thrown within the try block, or when a catch matching the thrown exception's class is not present) will continue after that last catch block defined in sequence
  • Exceptions can be thrown (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().
  • In PHP 5.5 and later, a finally block may also be specified after the 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.
  • 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.

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