using-statement

I'm fairly new to C++, but my understanding is that a #include statement will essentially just dump the contents of the #included file into the location of that statement. This means that if I have a number of '#include' and 'using' statements in my header file, my implementation file can just #include the header file, and the compiler won't mind if I don't repeat the other statements. What about people though? My main concern is that if I don't repeat the '#include', 'using', and also 'typedef' (now that I think of it) statements, it takes that information away from the file in which it's

Suppose I have a method like so: public byte[] GetThoseBytes() { using (System.IO.MemoryStream ms = new System.IO.MemoryStream()) { ms.WriteByte(1); ms.WriteByte(2); return ms.ToArray(); } } Would this still dispose the 'ms' object? I'm having doubts, maybe because something is returned before the statement block is finished. Thanks, AJ. Yes. using (x = e) { s } is sugar for { x = e; try { s } finally { x.Dispose(); } } Yes, Using creates a try..finally block , so it disposes the ms (and even does a null check in case you set ns to null). Yes, the whole idea behind the Using statement is that

Take the following example... Using cn As New SqlConnection(ConnectionString) Try Dim cmd As SqlCommand = New SqlCommand With cmd .Connection = cn .Connection.Open() .CommandText = "dbo.GetCustomerByID" .CommandType = CommandType.StoredProcedure .Parameters.Add("@CustomerID", SqlDbType.Int, 4) .Parameters("@CustomerID").Value = CustomerID End With da = New SqlDataAdapter(cmd) da.Fill(ds, "Customer") Catch ex As Exception End Try End Using From my research today is sounds as though this is basically okay but the SqlCommand is not being disposed of. Question -> Which of the following examples is

So a using statement automatically calls the dispose method on the object that is being "used", when the using block is exited, right? But when is this necessary/beneficial? For example let's say you have this method: public void DoSomething() { using (Font font1 = new Font("Arial", 10.0f)) { // Draw some text here } } Is it necessary to have the using statement here, since the object is created in the method? When the method exits, wont the Font object be disposed of anyway? Or does the Dispose method get run at another time after the method exits? For example if the method was like this:

As Eric Gunnerson shows in this blog post, in C# you can nest using statements as: using (StreamWriter w1 = File.CreateText("W1")) using (StreamWriter w2 = File.CreateText("W2")) { // code here } Is there a similar way to do it in VB.Net? I want to avoid too many indentation levels. SLaks Like this: Using a As New Thingy(), _ b As New OtherThingy() ... End Using Well, you can do: Using w1 = File.CreateText("W1"), w2 = File.CreateText("W2") ' Code goes here. ' End Using 来源： https://stackoverflow.com/questions/3345303/nested-using-statements