Re: Check whether a file handle is open

From:
"Giovanni Dicanio" <giovanni.dicanio@invalid.com>
Newsgroups:
microsoft.public.vc.language
Date:
Mon, 2 Jun 2008 19:46:41 +0200
Message-ID:
<u6ie0jNxIHA.3968@TK2MSFTNGP04.phx.gbl>
"Faisal" <faisalm83@gmail.com> ha scritto nel messaggio
news:e98b893d-b0eb-4628-9058-588542ba7150@x1g2000prh.googlegroups.com...

But how i could avoid multiple closing of a file handle.


I would wrap the file handle into a C++ class, e.g. FileHandle.
In the destructor of this class, you close the file.

(I read in your initial post that you open the file with _open, so your
handle is an 'int'.
So, you can put a member variable of type 'int' in your C++ class, make it
private, and expose a public accessor to that handle.
In the destructor, you can use _close to close the file.)

Instead of using the "raw" 'int' file handle, you can use this C++
'FileHandle' class. You can wrap this class using a smart pointer like
shared_ptr.
So, in your code, you refer to FileHandle using the shared_ptr smart
pointer.

shared_ptr automatically manages a reference count internally; so, when
there is no more "client" using the file handle class, the destructor of
your 'FileHandle' class is called, and the file handle is closed.

Smart pointers like shared_ptr are good tools for managing non-memory
resources (like file handles, as in your case, or textures, etc.).

HTH,
Giovanni

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