Re: OT: Checking if any chars available on stdin under Windows

Oops, meant to reply off list. And I also realised I didn't read the
question properly.

sorry!

----- Original Message ----- 
From: "Colin Fahey" <[email protected]>
To: <[email protected]>
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
>
>
>
>
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