Re: C90 fpeek

"Keith Thompson" <Keith.S.Thompson+u@gmail.com> wrote in message
news:87plkc6bgm.fsf@nosuchdomain.example.com...

"Paul Edwards" <mutazilah@gmail.com> writes:
[...]

With the benefit of hindsight, is there any reason why fpeek
couldn't have been added to C90, with implementations
being allowed with just a macro that returns some sort of
"unsupported"?
>
If fpeek (or similar) makes sense, can someone suggest an
appropriate interface?

[...]
>
It would help to know what "fpeek" is supposed to do.  There no such
function in any edition of the C standard or in any implementation
that I'm aware of.

fpeek would tell you whether there are any characters available
to be read, on a bidirectional data stream, opened with r+b or
whatever.

For an ordinary disk file, it wouldn't necessarily do anything,
and just return with "unknown" or whatever, for the application
to decide what to do.

But for a serial port/modem connected to a BBS, the infrastructure
would likely already know if there are characters sitting at the COM
port (or some corresponding buffer), so it would be in a position to
confirm/deny the presence of pending characters to be read.

It also occurred to me that games could use this, fpeek of stdin to
see if a key has been pressed.

Apologies for not making this clearer in the original post.

BFN. Paul.