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From: pete@iris49.UUCP (Pete Ware)
Newsgroups: comp.windows.x
Subject: Re: XtAppAddInput and pipes
Message-ID: <9010121709.AA05284@iris49.biosym.com>
Date: 12 Oct 90 17:09:31 GMT
References: <2068@cybaswan.UUCP>
Sender: root@athena.mit.edu (Wizard A. Root)
Organization: The Internet
Lines: 36


eejames> My questions are:

eejames> 1) Why does the program work fine with the keyboard attached
eejames> to stdin, but not with a pipe attched?
The program providing input is probably exiting which closes the pipe.

eejames> 2) Is there a simple fix?
Yes, change your function, input_fn() to something like:

void input_fn(client_data, source, id)
caddr_t client_data;
int	*source;
XtInputId *id;
{
  int time;

  if (scanf("%d",&time) == EOF) {
	XtRemoveInput (*id);
	return;
  }
  printf("time is %d\n",time);

  /* other processing etc */
}

- You might also consider using using gets() so you don't block if the
  user just enters a return (scanf keeps looking for input).
- You might want to use the client_data to pass in the actual file pointer
  so it can work for any source of input.
- You might want to close the file pointer when EOF is reached.

--pete
Pete Ware / Biosym / San Diego CA / (619) 546-5532
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