Will the clean-up logic still get called if an exception is thrown from within a using statement?

Question

I have some questions about using the using keyword. I have the following code:

try {
   using (System.Net.WebResponse response = httpWebRequest.GetResponse()) {
      throw new Exception("Example");
   }
} 

catch ( Exception ex ) { 
}

My question is, when the exception occurs will it close the connection? Or do I have to close the connection inside the catch?

Answer 1

Yes, it will close the connection.

The entire point of a using is that it will dispose the object when you leave the scope of the using, even if it is through an exception.

a using block is, under the hood, implemented using a try/finally block.

This is easy enough to test experimentally as well:

public class Foo : IDisposable
{
    public void Dispose()
    {
        Console.WriteLine("I was disposed!");
    }
}

private static void Main(string[] args)
{
    try
    {
        using (var foo = new Foo())
            throw new Exception("I'm mean");
    }
    catch { }
 }

And the output is:

I was disposed!