Does a C# using statement perform try/finally?

Question

Suppose that I have the following code:

private void UpdateDB(QuoteDataSet dataSet, Strint tableName)
{
    using(SQLiteConnection conn = new SQLiteConnection(_connectionString))
    {
        conn.Open();
        using (SQLiteTransaction transaction = conn.BeginTransaction())
        {
            using (SQLiteCommand cmd = new SQLiteCommand("SELECT * FROM " + tableName, conn))
            {
                using (SQLiteDataAdapter sqliteAdapter = new SQLiteDataAdapter())
                {
                    sqliteAdapter.Update(dataSet, tableName);
                }
            }
            transaction.Commit();
        }
    }
}

The C# documentation states that with a using statement the object within the scope will be disposed and I've seen several places where it's suggested that we don't need to use try/finally clause.

I usually surround my connections with a try/finally, and I always close the connection in the finally clause. Given the above code, is it reasonable to assume that the connection will be closed if there is an exception?

Answer 1

You are correct; the using statement compiles to a try / finally block.

The compiler transforms using(resource) statement; into the following code:

{
   ResourceType resource = expression;
   try {
      statement;
   }
   finally {
      if (resource != null) ((IDisposable)resource).Dispose();
   }
}

(The cast to IDisposable is in case ResourceType implements IDisposable explicitly.