Python Exception Handling Quiz

Study Notes

Exception Handling

Exception Handling: Used to handle errors during program execution, occurring due to invalid input or unforeseen scenarios.
Exception: An error encountered during program execution, distinct from syntax errors.
Try Block: Contains code that might raise exceptions.
Except Block: Handles specific exceptions, executing code when they occur.
Else Block: Executes code if an exception is not raised in the try block.
Finally Block: Executes code regardless of whether an exception occurred or not.

Types of Exceptions

Zero Division Error: Occurs when dividing by zero, a fundamental mathematical error.
Name Error: Encountered when using a variable not yet defined.
Value Error: Raised when a function receives an argument of the wrong type.
Index Error: Occurs when accessing an element that doesn't exist in a sequence (e.g. list, string).

Python Exceptions

Built-in Exceptions: Exceptions pre-defined in Python, including those mentioned above.
User-defined Exceptions: Specific errors that are created by programmers, usually to handle custom error conditions.

User-defined Exception Example:

Creating a User-defined Exception: Use the class syntax, inheriting from Python's Exception class.
Raising a User-defined Exception: Use the raise keyword, triggering the exception.
Catching a User-defined Exception: Use the except block, specifying the custom exception class.
Example: If input is 10 for a variable, raise the InvalidInputError.
InvalidInputError class is defined to denote a specific user error.
When InvalidInputError occurs, a message is displayed.

General Rule:

Specificity in Except Blocks: When possible, use the specific exception name, allowing the code to handle only the relevant exception.
Default Except Block: Using a bare except block catches all exceptions, which can be useful for handling unexpected errors or for debugging.
Importance of Exception Handling: Safeguards code from crashing due to unexpected events or errors, ensuring program stability and avoiding unintended consequences.

Exception Handling

Used to handle errors that occur during program execution.
Errors can be caused by invalid input or unforeseen circumstances.
An exception is an error that occurs during program execution, distinct from a syntax error.

Exception Handling Mechanisms

Try Block: Code that might raise exceptions is placed inside the try block.
Except Block: Specifies the exception to handle and runs the code within it when the specified exception occurs.
Else Block: Executes code if no exceptions are raised in the try block.
Finally Block: Runs regardless of whether an exception occurred or not.

Types of Built-in Exceptions

ZeroDivisionError: Occurs when dividing by zero.
NameError: Raises when trying to access a variable that does not exist.
ValueError: Raises when a function receives an argument of an incorrect type.
IndexError: Occurs when trying to access an element that doesn't exist in a sequence, such as a list or string.

User-defined Exceptions

Exceptions created by programmers to handle custom error conditions.
Created using the 'class' syntax, inheriting from Python's Exception class.
Raised using the 'raise' keyword.
Caught by the except block, specifying the custom exception class.

Example of Raising a User-defined Exception

A InvalidInputError exception is raised if a variable is assigned the value of 10.
This custom exception class indicates that the input provided is not valid.
When the InvalidInputError is raised, a user-defined message is displayed.

General Rules for Exception Handling

Use specific exception types in the except blocks to improve code clarity and handle only the intended errors.
A bare except block catches all exceptions, useful for handling unexpected errors or during debugging.

Importance of Exception Handling

Prevents code from crashing due to unforeseen events or errors, ensuring program stability and avoiding unintended consequences.
Allows the program to continue execution despite encountering errors.

Description

Test your knowledge on exception handling in Python, including various types of exceptions and their handling structures such as try, except, else, and finally blocks. This quiz covers fundamental concepts that are essential for effective programming in Python.