What are industry standard best practices for implementing custom exceptions in C#?

Question

What are industry standard best practices for implementing custom exceptions in C#?

I have checked Google and there's a great number of recommendations, however I don't know which ones hold more credibility.

If anybody has any links to authoritative articles, that would also be helpful.

Answer 1

The standard for creating custom exceptions is to derive from Exception. You can then introduce your own properties/methods and overloaded constructors (if applicable).

Here is a basic example of a custom ConnectionFailedException which takes in an extra parameter which is specific to the type of exception.

[Serializable] public class ConnectionFailedException : Exception {     public ConnectionFailedException(string message, string connectionString)         : base(message)     {         ConnectionString = connectionString;     }      public string ConnectionString { get; private set; } } 

In the application this could be used in scenarios where the application is attempting to connect to a database e.g.

try {     ConnectToDb(AConnString); } catch (Exception ex) {     throw new ConnectionFailedException(ex.Message, AConnString); } 

It's up to you to then handle the ConnectionFailedException at a higher level (if applicable)

Also have a look at Designing Custom Exceptions and Custom Exceptions

Answer 2

Here is the code to create a custom exception:

using System; using System.Runtime.Serialization;  namespace YourNamespaceHere {     [Serializable()]     public class YourCustomException : Exception, ISerializable     {         public YourCustomException() : base() { }         public YourCustomException(string message) : base(message) { }         public YourCustomException(string message, System.Exception inner) : base(message, inner) { }         public YourCustomException(SerializationInfo info, StreamingContext context) : base(info, context) { }     } } 

See also: http://www.capprime.com/software_development_weblog/2005/06/16/CreatingACustomExceptionClassInC.aspx