Custom Domain Exception in C# - Example You Can Run Online

Introduction

A named exception communicates intent more clearly than a generic Exception.

The custom type retains normal exception behavior while making the catch clause precise.

Runnable C# example

C#

Program.cs

using System;
class InsufficientStockException(string message) : Exception(message) { }
class Program
{
    static void Reserve(int available, int requested)
    {
        if (requested > available) throw new InsufficientStockException("Not enough stock");
    }
    static void Main()
    {
        try { Reserve(2, 3); }
        catch (InsufficientStockException error) { Console.WriteLine(error.Message); }
    }
}

Result of running the code

Not enough stock

Practice with the debugger

Set a breakpoint on an important assignment or condition, click Debug, and inspect the local values before stepping to the next line.

Practice with a challenge

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