Will closing a FileStream close the StreamReader?

Question

If I use a FileStream to create a StreamReader, will the StreamReader close when I close the FileStream or will I need to close the StreamReader too?

public void ReadFile()
{
    var file = new FileStream("c:\file.txt", FileMode.Open, FileAccess.Read);
    var reader = new StreamReader(file);

    try
    {
     txtFile.Text = reader.ReadToEnd();
    }
    catch (Exception)
    {
     throw;
    }
    finally
    {
     file.Close();
    }
}

Answer 1

Essentially yes. You don't actually have to close a StreamReader. If you do, all it does is closes the underlying stream.

@Bruno makes a good point about closing the outer-most wrapper. It is good practice to close the outer-most stream and let it close underlying streams in order to ensure all resources are released properly.

From Reflector...

public class StreamReader : TextReader
{
    public override void Close()
    {
        this.Dispose(true);
    }

    protected override void Dispose(bool disposing)
    {
        try
        {
            if ((this.Closable && disposing) && (this.stream != null))
            {
                this.stream.Close();
            }
        }
        finally
        {
            if (this.Closable && (this.stream != null))
            {
                this.stream = null;
                this.encoding = null;
                this.decoder = null;
                this.byteBuffer = null;
                this.charBuffer = null;
                this.charPos = 0;
                this.charLen = 0;
                base.Dispose(disposing);
            }
        }
    }
}

Answer 2

No. The best thing to do is close them in reverse order that you opened them.

Answer 3

No. You should close the reader instead. In practice, this might not present any problem but, the StreamReader could add some overhead that might need to be cleaned. So you should always close the top most wrapper.

Answer 4

You don't need to close the StreamReader because it doesn't own any unmanaged resources. Closing the FileStream is sufficient. You can rewrite your code with using like this:

public void ReadFile()
{
    using (var file = new FileStream("c:\file.txt", FileMode.Open, FileAccess.Read))
    {
        txtFile.Text = new StreamReader(file).ReadToEnd();
    }
}

In general if you are in doubt it is best to be safe and Dispose all IDisposable objects when you have finished using them.

public void ReadFile()
{
    using (FileStream file = new FileStream("c:\file.txt", FileMode.Open, FileAccess.Read))
    {
        using (StreamReader streamReader = new StreamReader(file))
        {
            txtFile.Text = streamReader.ReadToEnd();
        }
    }
}

Answer 5

You could also just use the File.ReadAllText method:

txtFile.Text = File.ReadAllText(@"c:\file.txt");