Message-ID: <87BC54A997CCD01198930020AFF6011C040F43@IS~RKKPRGOP02>
From: "Holejsovsky, Pavel" <PHolejs AT rkk DOT cz>
To: Tron Thomas <tron DOT thomas AT sierra DOT com>
Cc: djgpp AT delorie DOT com
Subject: RE: Can't get YACC parser to run
Date: Fri, 6 Jun 1997 04:17:37 +0200
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

Assigning some valid descriptor to yyin will help. For example:

	yyin = stdin;

for reading from standard input
or

	if ((yyin = fopen("infile", "r")) == NULL)
		return -1;

for reading from the file "infile".

> -----Original Message-----
> From:	Tron Thomas [SMTP:tron DOT thomas AT sierra DOT com]
> Sent:	Thursday, June 05, 1997 8:07 PM
> To:	djgpp AT delorie DOT com
> Subject:	Can't get YACC parser to run
> 
> I reading the book "Lex and Yacc" by John R. Levine, Tonay Mason, and
> Doug Brown.  I am using Flex version 2.5.3 and Bison version 1.25 for
> MS-DOS to run their examples, and I'm compiling the programs using
> Visual C++ 4.2 on Windows '95.
> 
> I created the program in example 1-7 (a Yacc Parser) of chapter one,
> but
> I'm not sure how I'm supposed to run it.  When I just try to launch
> it,
> the program crashes.  This is because the main function in the file
> ch1-05.y is defined as follows:
> 
> extern FILE *yyin;
> 
> main( )
> {
> 	while(!feof(yyin)){
> 		yyparse( );
> 	}
> }
> 
> When I trace through this code yyin = 0 causing the program to crash
> on
> the call to feof.
> 
> Can somebody tell me what I need to do to get this program to run?