Does the C# "finally" block ALWAYS execute? [duplicate]

Question

Possible Duplicate:
Will code in a Finally statement fire if I return a value in a Try block?

Consider the following code C# code. Does the "finally" block execute?

public void DoesThisExecute() {    string ext = "xlsx";    string message = string.Empty;    try {       switch (ext) {          case "xls": message = "Great choice!"; break;          case "csv": message = "Better choice!"; break;          case "exe": message = "Do not try to break me!"; break;          default:             message = "You will not win!";             return;       }    }    catch (Exception) {       // Handle an exception.    }    finally {       MessageBox.Show(message);    } } 

Ha, after I got done writing this, I realized I could have done tested this myself in Visual Studio. However, please feel free to answer!

Answer 1

No it does not. It will always execute provided the application is still running (except during a FastFail exception, MSDN link, like others noted). It will execute when it exits the try/catch portion of the block.

It will NOT execute if the application crashes: gets killed through a kill process command etc. This is highly important, because if you write code that absolutely expects it to run, like manually doing a roll back, and if not other wise it will automatically commit, you can run into a scenario the application aborts before that happens. Honestly, this is an outside scenario, but it is important to take note of in those situations.

Answer 2

From MSDN C# specification of the try statement:

The statements of a finally block are always executed when control leaves a try statement. This is true whether the control transfer occurs as a result of normal execution, as a result of executing a break, continue, goto, or return statement, or as a result of propagating an exception out of the try statement.

Source

There are the cases where the finally block will not execute:

1. Environment.FailFast
2. Uncatchable exception types
3. Power Failure