Do we need to close a C# BinaryWriter or BinaryReader in a using block?

Question

Having this code:

using (BinaryWriter writer = new BinaryWriter(File.Open(ProjectPath, FileMode.Create)))
{
   //save something here
}

Do we need to close the BinaryWriter? If not, why?

Answer 1

So long as it's all wrapped up in a using block then you don't need to explicitly call Close.

The using block will ensure that the object is disposed, and the Close and Dispose methods are interchangeable on BinaryWriter. (The Close method just calls Dispose behind the scenes.)

Answer 2

Putting it in a using statement as per your code example will call Dispose, which closes the underlying stream, so no. You can see this through Reflector:

protected virtual void Dispose(bool disposing)
{
    if (disposing)
    {
        this.OutStream.Close();
    }
}