Understanding Streams and their lifetime (Flush, Dispose, Close)

Question

Note: I\'ve read the following two questions already:

Can you explain the concept of streams?

C# using streams

I\'m coding in C#

1. In alm

Answer 1

Disposing a stream closes it (and probably doesn't do much else.) Closing a stream flushes it, and releases any resources related to the stream, like a file handle. Flushing a stream takes any buffered data which hasn't been written yet, and writes it out right away; some streams use buffering internally to avoid making a ton of small updates to relatively expensive resources like a disk file or a network pipe.

You need to call either Close or Dispose on most streams, or your code is incorrect, because the underlying resource won't be freed for someone else to use until the garbage collector comes (who knows how long that'll take.) Dispose is preferred as a matter of course; it's expected that you'll dispose all disposable things in C#. You probably don't have to call Flush explicitly in most scenarios.

In C#, it's idiomatic to call Dispose by way of a using block, which is syntactic sugar for a try-finally block that disposes in the finally, e.g.:

using (FileStream stream = new FileStream(path))
{
    // ...
}

is functionally identical to

FileStream stream;

try
{
    stream = new FileStream(path);
    // ...
}
finally
{
    if (stream != null)
        stream.Dispose();
}