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From: rjohnson@shell.com (Roy Johnson)
Newsgroups: comp.lang.c
Subject: Re: input to a function
Message-ID: <RJOHNSON.91Jun4100023@olorin.shell.com>
Date: 4 Jun 91 15:00:23 GMT
References: <1991May30.191116.19256@ux1.cso.uiuc.edu>
Sender: usenet@shell.shell.com (USENET News System)
Organization: Shell Development Company, Bellaire Research Center, Houston, TX
Lines: 42
In-Reply-To: nnj20229@uxa.cso.uiuc.edu's message of 30 May 91 19:11:16 GMT

In article <1991May30.191116.19256@ux1.cso.uiuc.edu> nnj20229@uxa.cso.uiuc.edu (Nesha Nicole Jones) writes:
>
>   I wrote a program that acts like a grep only it greps the line you are
>   looking for and the line above it.  I would like to be able to do 
>   something like:
>	   rest "restart" /usr/bin/adm/sa/sar24 
>			      or
>	   rest "restart" < /usr/bin/adm/sa/sar24
>
>
>   currently my program does the second of the two listed above.  If I use
>   file pointers and fopen will the program still work if I try to pipe input
>   into it?

     FILE *freopen(filename, type, stream)
     char *filename, *type;
     FILE *stream;

    freopen() opens the file named by  filename  and  associates
     the  stream pointed to by stream with it.  The type argument
     is used just as in fopen.  The original  stream  is  closed,
     regardless  of whether the open ultimately succeeds.  If the
     open succeeds,  freopen()  returns  the  original  value  of
     stream.

     freopen() is typically used to attach the preopened  streams
     associated with stdin, stdout, and stderr to other files.

So
if ((argc == 3) && (freopen(argv[2], "r", stdin) != stdin)) {
  perror(argv[2]);
  exit(1);
}

in your command line parsing phase should make the file
opening transparent to your program (no messy FILE pointers).

  
--
=============== !You!can't!get!here!from!there!rjohnson ===============
Feel free to correct me, but don't preface your correction with "BZZT!"
Roy Johnson, Shell Development Company