Exception hierarchy in .NET in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the base class for all exceptions in .NET?

The base class for all exceptions in .NET is <strong>System.Exception</strong>. All other exceptions inherit from this class.

intermediate

What is the difference between System.Exception and System.SystemException?

<code>System.Exception</code> is the root class for all exceptions. <code>System.SystemException</code> is a subclass used for exceptions thrown by the runtime, like <code>NullReferenceException</code> or <code>IndexOutOfRangeException</code>.

intermediate

Name two common subclasses of System.SystemException.

Two common subclasses of System.SystemException are NullReferenceException and IndexOutOfRangeException. These are used for runtime errors.

beginner

What is the purpose of System.IO.IOException in the exception hierarchy?

<code>System.IO.IOException</code> is a subclass of <code>System.Exception</code> that handles errors related to input/output operations, such as file access problems.

beginner

Why should you catch specific exceptions instead of catching System.Exception directly?

Catching specific exceptions helps you handle different error types properly and avoid hiding unexpected errors. Catching System.Exception can make debugging harder and may catch exceptions you don't intend to handle.

Which class is the direct parent of System.NullReferenceException?

A System.SystemException

B System.ApplicationException

C System.Exception

D System.IO.IOException

System.NullReferenceException inherits from System.SystemException, which is for runtime exceptions.

Which exception class should you use for errors caused by invalid arguments?

A System.ArgumentException

B System.IO.IOException

C System.NullReferenceException

D System.InvalidOperationException

System.ArgumentException is used when a method receives an invalid argument.

What is the root class of all exceptions in .NET?

A System.SystemException

B System.Exception

C System.ApplicationException

D System.Object

System.Exception is the root class for all exceptions.

Which exception type is best for handling file read/write errors?

A System.InvalidOperationException

B System.NullReferenceException

C System.ArgumentException

D System.IO.IOException

System.IO.IOException is designed for input/output errors like file access.

Why is catching System.Exception generally discouraged?

A It catches too few exceptions

B It only catches runtime exceptions

C It can hide unexpected errors and make debugging harder

D It is deprecated in .NET

Catching System.Exception can hide unexpected errors and make debugging difficult.

Explain the main branches of the exception hierarchy in .NET and their purposes.

Think about runtime vs application exceptions.

Describe why it is important to catch specific exceptions rather than the base Exception class.

Consider what happens if you catch everything at once.