Custom exception classes in PHP - Cheat Sheet & Quick Revision

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beginner

What is a custom exception class in PHP?

A custom exception class in PHP is a user-defined class that extends the built-in Exception class. It allows you to create specific error types for your application, making error handling clearer and more organized.

beginner

How do you define a custom exception class in PHP?

You define a custom exception class by creating a new class that extends the Exception class. For example:<br><pre>class MyException extends Exception {}</pre>

intermediate

Why use custom exception classes instead of the base Exception class?

Custom exception classes help you identify and handle specific error types separately. This makes your code easier to read and maintain, and allows different actions for different error conditions.

beginner

How can you catch a custom exception in PHP?

You catch a custom exception by using a try-catch block and specifying the custom exception class in the catch statement. For example:<br><pre>try {<br>  // code<br>} catch (MyException $e) {<br>  // handle MyException<br>}</pre>

intermediate

Can custom exception classes have their own methods and properties?

Yes, custom exception classes can have additional methods and properties to provide more information or functionality related to the specific error they represent.

How do you create a custom exception class in PHP?

A By importing a special library

B By extending the Exception class

C By using the throw keyword alone

D By creating a function named Exception

Custom exception classes are created by extending the built-in Exception class.

Which keyword is used to handle exceptions in PHP?

A catch

B handle

C try

D throw

The catch keyword is used to handle exceptions after a try block.

What is the benefit of using custom exception classes?

A They make code run faster

B They automatically fix errors

C They replace the need for try-catch

D They allow specific error handling

Custom exceptions allow you to handle different errors specifically and clearly.

Which of these is a valid way to catch a custom exception named MyException?

A catch (Error $e) {}

B catch (Exception $e) {}

C catch (MyException $e) {}

D catch (Throwable $e) {}

To catch a custom exception, you specify its class name in the catch block.

Can custom exception classes have extra methods?

A Yes, to add more info or behavior

B No, they must only inherit Exception

C Only if they are abstract

D Only if they don't extend Exception

Custom exception classes can have their own methods and properties.

Explain how to create and use a custom exception class in PHP.

Think about how you make a new class and how you handle errors.

Why might you want to create your own exception classes instead of using the default Exception?

Consider how different problems might need different solutions.