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From: jmartin@secola.Columbia.NCR.COM (John Martinez)
Newsgroups: comp.lang.c++
Subject: Treating cin, cout like files (or vice versa)
Message-ID: <365@secola.Columbia.NCR.COM>
Date: 29 Jun 91 19:12:17 GMT
Reply-To: jmartin@secola.Columbia.NCR.COM (John Martinez)
Organization: NCR NPD Columbia
Lines: 62

OK netters, here's my dumb question for the week:

Environment: DOS 4.01, Borland C++

Reader's Digest Version:
  I want to write a sort of template for "pipe" style programs which take 
  one input file, mess with it, and put the output to another file; the 
  code should default to using cin and cout unless filenames are on the 
  command-line.

  e.g. Both [all three] of these should do the same thing:
         cat filea | my_program > fileb      works, but so does
         my_program filea fileb              and maybe even [dare to dream :)]
         cat filea | my_program - fileb


sounds simple, right? And it probably is, but I can't seem to get anything 
which seems like it might work to compile!  :(

I want to do something like: (yes, I know _this_ code is _way_ wrong...)
**********
#include <fstream.h>

main (int argc, char *argv[]){

  ifstream in_stuff;
  ofstream out_stuff;

  if (argc >=1) 
	in_stuff = argv[1];
  else 
	in_stuff = cin;

  [ same sort of thing for out_stuff here....]

  [ code that uses in_stuff and out_stuff here and doesn't know or 
    care if we are using files or cin/cout goes here     ]
};

 - you get the picture. But none of the [>20] variations on this theme
I've tried seem to work; I'm lost in a hopeless tangle of ostreams, ofstreams,
ofstreams-withassigns,iostreams,ice_creams, etc.... !! :( :( :(

anybody feeling generous and want to tell me the secret? I won't even complain
if the answer comes along with an RTFM flame, although I must protest that I 
have been R'ing the FM, and if the information is in there, it's rather
deeply buried.

advTHANKSance,

-(-- John the miffed coder
send replies to jmartin@secola.Columbia.NCR.COM
....yes, upper/lower case in the address matters - very annoying :( :(

p.s. If anyone asks, I'll post or mail the working template when I have one.


-- 
John V.Martinez
NCR Network Products Division
jmartin@secola.Columbia.NCR.COM
(803)739-7671 vplus:633-7671