Re: [Flex-help] Digits followed by letters

[Will E. <wl...@us...>]

You really want to use bison to implement the grammar you have in mind.

(As well as fixing the errors in your flex input file below.)

--Will

On Friday, 26 February 2010, 10:35 pm +0600, "Dr. Muhammad Masroor Ali" <mma...@cs...> wrote:

> Thanks for the answer. Everything (lexing) goes fine until the last action
> line is added, I get a message in the line of unrecognized rule. Sorry to be a
> bother.
> 
> %{
> 
> 	#include <stdlib.h>
> 
> 	#include <malloc.h>
> 
> %}
> 
> 
> 
> 
> 
> DIGIT [0-9]
> 
> LETTER [a-zA-Z]
> 
> INTEGER {DIGIT}+/[^a-zA-Z]
> 
> ID 	{LETTER}({LETTER}|{LETTER})+
> 
> 
> 
> %%
> 
> 
> 
> {INTEGER}	{
>  fprintf(yyout, "<INT, %s>", yytext);
> }
> 
> 
> 
> 
> ---------- Original Message -----------
> From: Dan Haggarty <dan...@du...>
> To: "Dr. Muhammad Masroor Ali" <mma...@cs...>,
> fle...@li...
> Sent: Fri, 26 Feb 2010 08:45:34 -0500
> Subject: Re: [Flex-help] Digits followed by letters
> 
> > If an INT (and FLOAT) must always be followed by WS then you can use 
> > the '/' construct:
> > 
> > INT     {DIGIT}+/{WS}
> > FLOAT   {DIGIT}+\.{DIGIT}+/{WS}
> > 
> > Alternatively, if an INT can be followed by anything that isn't a
> > LETTER, you can use '/' along with '^':
> > 
> > INT     {DIGIT}+/[^a-zA-Z]
> > 
> > Dan
> > 
> > You wrote:
> > > I have got the following rules
> > >
> > > LETTER [a-zA-Z]
> > > DIGIT	[0-9]
> > > ID 	{LETTER}({LETTER}|{DIGIT})*
> > > INT	{DIGIT}+
> > > FLOAT	{DIGIT}+\.{DIGIT}+
> > > WS 	[ \t\n]
> > > %%
> > >
> > >
> > > Now by the above 123abc is treated as an INT followed  by an ID. But I want 
> > > to generate an error for this.  How do I do that?
> > >
> > > 123 abc should be okay to be treated as an INT followed  by an ID.
> > >
> > > Thanks in advance.
> > >
> ------- End of Original Message -------
> 
> 
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-- 
Will Estes (wl...@us...)
Flex Project Maintainer
http://flex.sourceforge.net/