gamedevlists-general

Re: [GD-General] OT: Checking if any chars available on stdin under Windows

[Mark W. <ma...@aw...>]

Ok, the solution appears to be to check _eof(0); - If it returns -1, there's
nothing on stdin.

I *think* that's the answer you're looking for.

Mark Webster

> ----- Original Message ----- 
> From: "Colin Fahey" <cp...@ea...>
> To: <gam...@li...>
> Sent: Friday, April 23, 2004 3:31 PM
> Subject: [GD-General] OT: Checking if any chars available on stdin under
> Windows
>
>
> >
> > 2004 April 22nd
> > Friday
> >
> > Off-Topic question here...but I just spent an hour doing Google
> > searching and reading other online documentation, and I'm not
> > finding any answers to the following:
> >
> > QUESTION:  How can I check if stdin (standard input) has any
> > characters available for reading under WINDOWS (not Linux)?
> >
> > I thought (cin.rdbuf()->in_avail()) would be the cool hacked
> > solution -- but even after doing Sleep(1000), cin.sync_with_stdio(),
> > and wackier and wackier things to try to make "cin" up-to-date,
> > so to speak, the expression above ALWAYS yields zero, whether or
> > not there are characters available on the input stream.
> > (Compiled using Visual C++ 6.0 under Windows 2000)
> >
> > If I have a command line like the following:
> >
> >         testapp
> >
> > then the following code blocks indefinitely:
> >
> >         int c = cin.peek();
> >
> > but if the command line is as follows:
> >
> >         more textfile.txt | testapp
> >
> > then the application does not block.  But in both
> > cases (cin.rdbuf()->in_avail()) is zero.
> >
> > How can "testapp" in the two command line examples
> > above DETECT which scenario (piped input or not) is
> > involved?  That, I guess, is my real goal.  I want to
> > know if the command line lacks the piping from
> > another app, since this means I shouldn't wait
> > forever for stdin data.
> >
> > I'd be willing to use a Win32 function to solve this
> > problem, but if it is really tricky, like creating a
> > thread, or something nutty, then it's probably not
> > worth it.  Bleah, under Linux one can actually use
> > fnctl() to change stdin to non-blocking mode (but,
> > I assume, still buffered), which makes this problem
> > go away -- but no fnctl() under Windows.
> >
> > Anyhow, probably avoiding piping data through stdin
> > is the REAL solution to all of this mess, but that
> > decision is not mine to make.
> >
> > --- Colin
> >
> >
> >
> >
> > -------------------------------------------------------
> > This SF.net email is sponsored by: The Robotic Monkeys at ThinkGeek
> > For a limited time only, get FREE Ground shipping on all orders of $35
> > or more. Hurry up and shop folks, this offer expires April 30th!
> > http://www.thinkgeek.com/freeshipping/?cpg=12297
> > _______________________________________________
> > Gamedevlists-general mailing list
> > Gam...@li...
> > https://lists.sourceforge.net/lists/listinfo/gamedevlists-general
> > Archives:
> > http://sourceforge.net/mailarchive/forum.php?forum_id=557
> >
> >
>

RE: [GD-General] OT: Checking if any chars available on stdin under Windows

[tweety <mi...@sy...>]

Just a shot in the dark here, but on windows wouldn't eof return true only
then it encounters ^Z? 

----------------------------------
Peace and love,
Tweety
mi...@sy... - twe...@us...
YahooID: tweety_04_01



-----Original Message-----
From: gam...@li...
[mailto:gam...@li...] On Behalf Of Mark
Webster
Sent: April 23, 2004 11:26 AM
To: gam...@li...
Subject: Re: [GD-General] OT: Checking if any chars available on stdin under
Windows

Ok, the solution appears to be to check _eof(0); - If it returns -1, there's
nothing on stdin.

I *think* that's the answer you're looking for.

Mark Webster

> ----- Original Message ----- 
> From: "Colin Fahey" <cp...@ea...>
> To: <gam...@li...>
> Sent: Friday, April 23, 2004 3:31 PM
> Subject: [GD-General] OT: Checking if any chars available on stdin under
> Windows
>
>
> >
> > 2004 April 22nd
> > Friday
> >
> > Off-Topic question here...but I just spent an hour doing Google
> > searching and reading other online documentation, and I'm not
> > finding any answers to the following:
> >
> > QUESTION:  How can I check if stdin (standard input) has any
> > characters available for reading under WINDOWS (not Linux)?
> >
> > I thought (cin.rdbuf()->in_avail()) would be the cool hacked
> > solution -- but even after doing Sleep(1000), cin.sync_with_stdio(),
> > and wackier and wackier things to try to make "cin" up-to-date,
> > so to speak, the expression above ALWAYS yields zero, whether or
> > not there are characters available on the input stream.
> > (Compiled using Visual C++ 6.0 under Windows 2000)
> >
> > If I have a command line like the following:
> >
> >         testapp
> >
> > then the following code blocks indefinitely:
> >
> >         int c = cin.peek();
> >
> > but if the command line is as follows:
> >
> >         more textfile.txt | testapp
> >
> > then the application does not block.  But in both
> > cases (cin.rdbuf()->in_avail()) is zero.
> >
> > How can "testapp" in the two command line examples
> > above DETECT which scenario (piped input or not) is
> > involved?  That, I guess, is my real goal.  I want to
> > know if the command line lacks the piping from
> > another app, since this means I shouldn't wait
> > forever for stdin data.
> >
> > I'd be willing to use a Win32 function to solve this
> > problem, but if it is really tricky, like creating a
> > thread, or something nutty, then it's probably not
> > worth it.  Bleah, under Linux one can actually use
> > fnctl() to change stdin to non-blocking mode (but,
> > I assume, still buffered), which makes this problem
> > go away -- but no fnctl() under Windows.
> >
> > Anyhow, probably avoiding piping data through stdin
> > is the REAL solution to all of this mess, but that
> > decision is not mine to make.
> >
> > --- Colin
> >
> >
> >
> >
> > -------------------------------------------------------
> > This SF.net email is sponsored by: The Robotic Monkeys at ThinkGeek
> > For a limited time only, get FREE Ground shipping on all orders of $35
> > or more. Hurry up and shop folks, this offer expires April 30th!
> > http://www.thinkgeek.com/freeshipping/?cpg=12297
> > _______________________________________________
> > Gamedevlists-general mailing list
> > Gam...@li...
> > https://lists.sourceforge.net/lists/listinfo/gamedevlists-general
> > Archives:
> > http://sourceforge.net/mailarchive/forum.php?forum_id=557
> >
> >
>



-------------------------------------------------------
This SF.net email is sponsored by: The Robotic Monkeys at ThinkGeek
For a limited time only, get FREE Ground shipping on all orders of $35
or more. Hurry up and shop folks, this offer expires April 30th!
http://www.thinkgeek.com/freeshipping/?cpg=12297
_______________________________________________
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Archives:
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Re: [GD-General] OT: Checking if any chars available on stdin under Windows

[<ma...@aw...>]

Well, if eof(0) returns -1, it means there was an error with file descriptor 0 (stdin) indicating that the stdin is not open. This tells us whether the program is being piped to or not. This is a simple non-blocking way to determine if the program can read from stdin or not.

You can verify this in MSVC help :)

Mark Webster

On Fri, Apr 23, 2004 at 04:33:38PM -0400, tweety wrote:
> Just a shot in the dark here, but on windows wouldn't eof return true only
> then it encounters ^Z? 
> 
> ----------------------------------
> Peace and love,
> Tweety
> mi...@sy... - twe...@us...
> YahooID: tweety_04_01
> 
> 
> 
> -----Original Message-----
> From: gam...@li...
> [mailto:gam...@li...] On Behalf Of Mark
> Webster
> Sent: April 23, 2004 11:26 AM
> To: gam...@li...
> Subject: Re: [GD-General] OT: Checking if any chars available on stdin under
> Windows
> 
> Ok, the solution appears to be to check _eof(0); - If it returns -1, there's
> nothing on stdin.
> 
> I *think* that's the answer you're looking for.
> 
> Mark Webster
> 
> > ----- Original Message ----- 
> > From: "Colin Fahey" <cp...@ea...>
> > To: <gam...@li...>
> > Sent: Friday, April 23, 2004 3:31 PM
> > Subject: [GD-General] OT: Checking if any chars available on stdin under
> > Windows
> >
> >
> > >
> > > 2004 April 22nd
> > > Friday
> > >
> > > Off-Topic question here...but I just spent an hour doing Google
> > > searching and reading other online documentation, and I'm not
> > > finding any answers to the following:
> > >
> > > QUESTION:  How can I check if stdin (standard input) has any
> > > characters available for reading under WINDOWS (not Linux)?
> > >
> > > I thought (cin.rdbuf()->in_avail()) would be the cool hacked
> > > solution -- but even after doing Sleep(1000), cin.sync_with_stdio(),
> > > and wackier and wackier things to try to make "cin" up-to-date,
> > > so to speak, the expression above ALWAYS yields zero, whether or
> > > not there are characters available on the input stream.
> > > (Compiled using Visual C++ 6.0 under Windows 2000)
> > >
> > > If I have a command line like the following:
> > >
> > >         testapp
> > >
> > > then the following code blocks indefinitely:
> > >
> > >         int c = cin.peek();
> > >
> > > but if the command line is as follows:
> > >
> > >         more textfile.txt | testapp
> > >
> > > then the application does not block.  But in both
> > > cases (cin.rdbuf()->in_avail()) is zero.
> > >
> > > How can "testapp" in the two command line examples
> > > above DETECT which scenario (piped input or not) is
> > > involved?  That, I guess, is my real goal.  I want to
> > > know if the command line lacks the piping from
> > > another app, since this means I shouldn't wait
> > > forever for stdin data.
> > >
> > > I'd be willing to use a Win32 function to solve this
> > > problem, but if it is really tricky, like creating a
> > > thread, or something nutty, then it's probably not
> > > worth it.  Bleah, under Linux one can actually use
> > > fnctl() to change stdin to non-blocking mode (but,
> > > I assume, still buffered), which makes this problem
> > > go away -- but no fnctl() under Windows.
> > >
> > > Anyhow, probably avoiding piping data through stdin
> > > is the REAL solution to all of this mess, but that
> > > decision is not mine to make.
> > >
> > > --- Colin
> > >
> > >
> > >
> > >
> > > -------------------------------------------------------
> > > This SF.net email is sponsored by: The Robotic Monkeys at ThinkGeek
> > > For a limited time only, get FREE Ground shipping on all orders of $35
> > > or more. Hurry up and shop folks, this offer expires April 30th!
> > > http://www.thinkgeek.com/freeshipping/?cpg=12297
> > > _______________________________________________
> > > Gamedevlists-general mailing list
> > > Gam...@li...
> > > https://lists.sourceforge.net/lists/listinfo/gamedevlists-general
> > > Archives:
> > > http://sourceforge.net/mailarchive/forum.php?forum_id=557
> > >
> > >
> >
> 
> 
> 
> -------------------------------------------------------
> This SF.net email is sponsored by: The Robotic Monkeys at ThinkGeek
> For a limited time only, get FREE Ground shipping on all orders of $35
> or more. Hurry up and shop folks, this offer expires April 30th!
> http://www.thinkgeek.com/freeshipping/?cpg=12297
> _______________________________________________
> Gamedevlists-general mailing list
> Gam...@li...
> https://lists.sourceforge.net/lists/listinfo/gamedevlists-general
> Archives:
> http://sourceforge.net/mailarchive/forum.php?forum_id=557
> 
> 
> 
> 
> -------------------------------------------------------
> This SF.net email is sponsored by: The Robotic Monkeys at ThinkGeek
> For a limited time only, get FREE Ground shipping on all orders of $35
> or more. Hurry up and shop folks, this offer expires April 30th!
> http://www.thinkgeek.com/freeshipping/?cpg=12297
> _______________________________________________
> Gamedevlists-general mailing list
> Gam...@li...
> https://lists.sourceforge.net/lists/listinfo/gamedevlists-general
> Archives:
> http://sourceforge.net/mailarchive/forum.php?forum_id=557
>