Custom error messages in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a custom error message in Python?

A custom error message is a specific message you write to explain why an error happened, making it easier to understand and fix.

beginner

How do you raise an error with a custom message in Python?

Use the raise keyword followed by an error type and a message in quotes, like raise ValueError('This is a custom message').

beginner

Why are custom error messages helpful?

They tell exactly what went wrong in your program, helping you or others fix problems faster.

intermediate

What is the syntax to catch an error and print its custom message?

Use a try block for code that might fail, and an except block to catch the error and print the message, like:<br>

try:
    ...
except ValueError as e:
    print(e)

intermediate

Can you create your own error type with a custom message?

Yes! You can make a new error class by inheriting from <code>Exception</code> and add a message to it.

How do you add a custom message when raising an error in Python?

A print('Custom message')

B throw ValueError('Custom message')

C error('Custom message')

D raise ValueError('Custom message')

In Python, raise is used to trigger errors with optional messages.

What keyword is used to handle errors and access their messages?

A catch

B except

C handle

D error

Python uses try and except blocks to catch and handle errors.

Which of these is a correct way to print a custom error message from an exception?

A except Exception as e: print(e)

B except Exception: print('e')

C try: print(e)

D raise Exception print(e)

You catch the exception as a variable and then print that variable to show the message.

What is the base class for creating custom error types in Python?

A Exception

B BaseError

C Error

D CustomError

All custom errors should inherit from the built-in Exception class.

Why should you use custom error messages?

A To confuse users

B To make errors harder to find

C To explain what went wrong clearly

D To avoid writing code

Custom messages help explain errors clearly, making debugging easier.

Explain how to raise an error with a custom message and how to catch it to display the message.

Think about how you tell Python to stop with a message and how you catch that message to show it.

Describe how to create your own error type with a custom message in Python.

Imagine making your own kind of error that behaves like built-in errors but with your own message.