Exception hierarchy in .NET in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a custom exception class that inherits from the base exception class.

C Sharp (C#)

public class MyCustomException : [1] {
}

Drag options to blanks, or click blank then click option'

AException

BSystemException

CApplicationException

DBaseException

Attempts:

3 left

💡 Hint

Common Mistakes

Inheriting from SystemException instead of Exception

Using a non-existent base class like BaseException

The base class for all exceptions in .NET is Exception. Custom exceptions should inherit from it.

2fill in blank

medium

Complete the code to catch all exceptions derived from the base exception class.

C Sharp (C#)

try {
    // some code
} catch ([1] ex) {
    Console.WriteLine(ex.Message);
}

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ASystemException

BBaseException

CApplicationException

DException

Attempts:

3 left

💡 Hint

Common Mistakes

Catching SystemException only catches system exceptions, not all exceptions.

Using a non-existent class like BaseException.

Catching Exception will catch all exceptions derived from it, which includes all standard exceptions.

3fill in blank

hard

Fix the error in the code by choosing the correct base class for a custom exception.

C Sharp (C#)

public class DataNotFoundException : [1] {
    public DataNotFoundException(string message) : base(message) {}
}

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AApplicationException

BSystemException

CException

DErrorException

Attempts:

3 left

💡 Hint

Common Mistakes

Using SystemException which is meant for system exceptions.

Using a non-existent class like ErrorException.

Custom exceptions should inherit from ApplicationException or directly from Exception. Here, Exception is the best choice for custom exceptions as ApplicationException is generally not recommended for new code.

4fill in blank

hard

Fill both blanks to create a dictionary mapping exception types to their descriptions.

C Sharp (C#)

var exceptionDescriptions = new Dictionary<string, string> {
    {"[1]", "Base class for all exceptions"},
    {"[2]", "Base class for system exceptions"}
};

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AException

BSystemException

CApplicationException

DBaseException

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing ApplicationException with SystemException.

Using a non-existent class like BaseException.

Exception is the base class for all exceptions, and SystemException is the base class for system exceptions.

5fill in blank

hard

Fill all three blanks to create a LINQ query that selects exception names and filters system exceptions.

C Sharp (C#)

var systemExceptions = from ex in exceptions
                       where ex is [1]
                       select new { Name = ex.GetType().[2] , Type = ex.[3] };

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ASystemException

BName

CGetType

DMessage

Attempts:

3 left

💡 Hint

Common Mistakes

Using GetType() instead of the Name property for the type name.

Using the wrong property for the message.

The query filters exceptions that are SystemException or derived. It selects the exception's type name using the Name property and the exception message.