Exception hierarchy in .NET in C Sharp (C#) - Mini Project: Build & Apply

Exception hierarchy in .NET

📖 Scenario: Imagine you are building a simple program that processes user input and might encounter different types of errors. You want to understand how exceptions are organized in .NET so you can handle them properly.

🎯 Goal: You will create a small program that defines a few exceptions following the .NET exception hierarchy and demonstrates catching them in order.

📋 What You'll Learn

Create a base exception class called MyAppException that inherits from System.Exception.

Create two derived exception classes: InputException and ProcessingException that inherit from MyAppException.

Write a method ProcessInput that throws InputException if input is empty and ProcessingException if input is "error".

Use a try-catch block to catch exceptions in order: first InputException, then ProcessingException, then MyAppException, and finally Exception.

💡 Why This Matters

🌍 Real World

Understanding exception hierarchy helps you write robust programs that can handle errors clearly and maintainably.

💼 Career

Many software development jobs require good error handling skills to build reliable applications.

1

Create base exception class

Create a class called MyAppException that inherits from System.Exception and has a constructor that takes a string message and passes it to the base constructor.

C Sharp (C#)

# Your code here

Need a hint?

Remember to inherit from Exception and call the base constructor with the message.

2

Create derived exception classes

Create two classes called InputException and ProcessingException that both inherit from MyAppException. Each should have a constructor that takes a string message and passes it to the base constructor.

C Sharp (C#)

using System;

class MyAppException : Exception
{
    public MyAppException(string message) : base(message) { }
}

# Your code here

Need a hint?

Both classes inherit from MyAppException and call the base constructor with the message.

3

Write method that throws exceptions

Write a static method called ProcessInput that takes a string input. If input is empty, throw an InputException with message "Input is empty". If input is "error", throw a ProcessingException with message "Processing error occurred". Otherwise, do nothing.

C Sharp (C#)

using System;

class MyAppException : Exception
{
    public MyAppException(string message) : base(message) { }
}

class InputException : MyAppException
{
    public InputException(string message) : base(message) { }
}

class ProcessingException : MyAppException
{
    public ProcessingException(string message) : base(message) { }
}

class Program
{
    static void ProcessInput(string input)
    {
        // Throw exceptions based on input
        # Your code here
    }
}

Need a hint?

Use string.IsNullOrEmpty(input) to check for empty input and throw the correct exceptions.

4

Catch exceptions in order

In the Main method, call ProcessInput three times with inputs: empty string, "error", and "ok". Use a try-catch block to catch exceptions in this order: InputException, ProcessingException, MyAppException, and Exception. Print the caught exception's message with Console.WriteLine. If no exception occurs, print "Input processed successfully".

C Sharp (C#)

using System;

class MyAppException : Exception
{
    public MyAppException(string message) : base(message) { }
}

class InputException : MyAppException
{
    public InputException(string message) : base(message) { }
}

class ProcessingException : MyAppException
{
    public ProcessingException(string message) : base(message) { }
}

class Program
{
    static void ProcessInput(string input)
    {
        if (string.IsNullOrEmpty(input))
        {
            throw new InputException("Input is empty");
        }
        else if (input == "error")
        {
            throw new ProcessingException("Processing error occurred");
        }
    }

    static void Main()
    {
        string[] inputs = { "", "error", "ok" };
        foreach (string input in inputs)
        {
            // Use try-catch to handle exceptions in order
            # Your code here
        }
    }
}

Need a hint?

Remember to catch exceptions from most specific to most general. Print the exception message or success message accordingly.