Custom exception classes in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a custom exception class in C#?

A custom exception class is a user-defined class that inherits from <code>Exception</code> or its subclasses to represent specific error conditions in your program.

beginner

How do you define a basic custom exception class in C#?

You create a class that inherits from <code>Exception</code> and provide constructors, for example:<br><pre>public class MyException : Exception { public MyException(string message) : base(message) {} }</pre>

intermediate

Why should you create custom exception classes instead of using general exceptions?

Custom exceptions help you clearly identify and handle specific error cases, making your code easier to read, debug, and maintain.

beginner

Which base class do all custom exceptions in C# usually inherit from?

They usually inherit from the <code>Exception</code> class, which is the base class for all exceptions in C#.

beginner

What is the purpose of calling base(message) in a custom exception constructor?

It passes the error message to the base <code>Exception</code> class so that the message can be accessed later when the exception is caught.

Which keyword is used to create a custom exception class in C#?

A try

B exception

C throw

D class

You use the class keyword to define a new class that inherits from Exception.

What should a custom exception class inherit from?

A System.Exception

B System.Console

C System.String

D System.Object

Custom exceptions should inherit from System.Exception to behave like standard exceptions.

Why do you call base(message) in a custom exception constructor?

A To catch the exception

B To initialize the base Exception with the error message

C To throw the exception immediately

D To log the error message

Calling base(message) passes the message to the base Exception class for proper error handling.

Which of these is a benefit of using custom exceptions?

A They automatically fix bugs

B They prevent exceptions from occurring

C They make error handling more specific and clear

D They replace the need for try-catch blocks

Custom exceptions help you identify and handle specific errors clearly.

Which constructor is commonly included in a custom exception class?

A A constructor that takes a string message

B A constructor that returns void

C A constructor that takes an int

D A constructor that takes no parameters and does nothing

A constructor that takes a string message allows you to pass an error description when throwing the exception.

Explain how to create a custom exception class in C# and why it is useful.

Think about class inheritance and error clarity.

Describe the role of the base Exception class when defining custom exceptions.

Base class is the foundation for all exceptions.