That appears to give me an error in lex:
%option noyywrap
%%
\x00 { return ZERO; }
.|\n { return *yytext; }
%%
—
Error:
flex -8 gmr.l
gcc -c lex.yy.c
gmr.l: In function ‘yylex’:
gmr.l:2:10: error: ‘ZERO’ undeclared (first use in this function); did you mean
‘EIO’?
\x00 { return ZERO; }
^~~~
EIO
gmr.l:2:10: note: each undeclared identifier is reported only once for each
function it appears in
Makefile:13: recipe for target 'lex.yy.o' failed
make: *** [lex.yy.o] Error 1
Bison likes it.
Tried quoting the \x00 but thats not right it appears.
> On Mar 30, 2021, at 16:15, Chris verBurg <cheetomons...@gmail.com> wrote:
>
>
> I don’t know how you’ve set up your flex/bison interface, but I’m guessing
> from your quoting that you have flex return each character as a token? Can
> you special-case 0 to not have the token value 0? That is, flex does this:
>
> \x00 { return ZERO; }
>
> And then in your grammar:
>
> %token ZERO
>
> and use ZERO instead of ‘\x00’?
>
> (Note: typed this on a phone..not 100% sure the syntax is right.)
>
> -Chris
>
>
>> On Mar 30, 2021, at 12:37 PM, Stephen Taylor via Users list for the GNU
>> Bison parser generator <help-bison@gnu.org> wrote:
>>
>> I am trying to parse binary files and obviously need to write rules that
>> include the 8-bit value 0x00 — flex appears to allow me to obtain an 8-bit
>> scanner using the -8 option. I seem to be able to use ‘\x01’ to ‘\xFF’ for
>> individual terminal symbols in Bison rules. Unfortunately, ‘\x00’ is used to
>> denote end of input. Looking at the output tables, there appears to be no
>> real reason to do this (other than convenience) and I am wondering if anyone
>> has a workaround?
>> Thanks !
>> Steve
>>
>>
>>
>>
>
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