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From: hollings@poona.cs.wisc.edu (Jeff Hollingsworth)
Newsgroups: comp.unix.wizards
Subject: Re: yacc & lex - cupla questions
Message-ID: <10916@spool.cs.wisc.edu>
Date: 30 Jul 90 16:39:45 GMT
References: <1990Jul26.175831.1216@uicbert.eecs.uic.edu> <32114@cup.portal.com>
Sender: news@spool.cs.wisc.edu
Reply-To: hollings@poona.cs.wisc.edu (Jeff Hollingsworth)
Organization: University of Wisconsin--Madison
Lines: 23

In article <32114@cup.portal.com>, chucka@cup.portal.com (Charles -
Anderson) writes:
|> 
|
|> >---------------------------------------------------------------------
|> >1.)  how does one redefine the i/o in a yacc/lex piece of code?  i.e.
|> >the code which is generated defaults to stdin and stdout for input and
|> >output, respectively.  i'd like to redefine these defaults w/o having 
|> >to hack on the intermediate c-code, since this is a live production 
|> >project; i'd like to be able to update and modify the program simply by 
|> >saying "make". 
|> 
|> You can use freopen, or if you wish another file use dup.
|> 

A cleaner approach is to use the file variable yyin.  Which lex uses to get 
its input.  Thus yyin = fopen(infile, "r") will do the redirection and leave
standard in alone.  Just do this before calling yyparse().


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Jeff Hollingsworth					Work: (608) 262-6617
hollings@cs.wisc.edu					Home: (608) 256-4839