c++ - syntax error, unexpected token, expecting end of file -

i following error when run parser file ( binary got after compiling flex/bison files). error: syntax error, unexpected tkn_primary, expecting end of file

here rule defined in flex code:

<primary_mme_state>{number} {  lexval = yytext();  std::cout<<"primary mme -->  "<<lexval<<std::endl;  yylval->strval = new std::string(lexval);  return token::tkn_primarymme;  } 

and understanding since value of tkn_primary 0 ( value defined end %token end 0 "end of file") instead of returning tkn_primary , expecting token end returned. please comment if understanding correct . , how tackle issue.

if tkn_primary , end have same value (or, in general, if 2 different tokens have same value), bison parser going act in unpredictable ways.

quoting bison manual:

it best, however, let bison choose numeric codes token types. bison automatically select codes don't conflict each other or normal characters.

i think that's best way of dealing problem.