What happens if StreamReader or StreamWriter are not closed?

I'm working on an assignment for a professor that is strict about LOC. For this reason I'd like to do the following:

(new StreamWriter(saveFileDialog.FileName)).Write(textBox.Text);

instead of

StreamWriter sw = new StreamWriter(saveFileDialog.FileName);
sw.Write(textBox.Text);
sw.Close();

In the first example I don't close the stream. Is this ok? Will it cause any security or memory problems?

You may not get any output, or incomplete output. Closing the writer also flushes it. Rather than manually calling Close at all, I'd use a using statement... but if you're just trying to write text to a file, use a one-shot File.WriteAllText call:

File.WriteAllText(saveFileDialog.FileName, textBox.Text);

Maybe your tutor is looking for:

File.WriteAllText(saveFileDialog.FileName, textbox.Text);

It's reasonable to prefer concise code, but not at the expense of readability or correctness.

Simplest solution without fout.Close() should be:

        using (StreamWriter fout = new StreamWriter(saveFileDialog.FileName))
        {
            fout.Write(textBox.Text);
        }

If you don't close it, you can't guarantee that it'll write out the last piece of data written to it. This is because it uses a buffer and the buffer is flushed when you close the stream.

Second, it will lock the file as open preventing another process from using it.

The safest way to use a filestream is with a using statement.

Short answer, the resources allocated for that operation will not be freed not to mention that it could pottentially lock that file.

Consider

using( var fout = new StreamWriter(saveFileDialog.FileName){ fout.write(textBox.Text); }

Any how GC will close it for you. But the thing is until the GC closes that stream you are unnecessary putting on hold to the resources

You can try with using blok in order to clean your no managed object

        using (var streamWriter = new StreamWriter(saveFileDialog.FileName))
        {
            streamWriter.Write(textBox.Text);
        }

Antarr Byrd

It would be a memory hazard.

I would always use StreamWriter in a 'using' statement

using(StreamWriter fout = new StreamWriter(saveFileDialog.FileName)
{
    fout.Write(textBox.Text);
}

来源：https://stackoverflow.com/questions/12783947/what-happens-if-streamreader-or-streamwriter-are-not-closed

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