Program to recognize strings ‘aaab’, ‘abbb’, ‘ab’ and ‘a’ using grammar (an b n , n>=0) . | Compiler Design Lab Programs | Yacc Programs

Yacc Part :

%token A B NL

%%

stmt : s NL { printf(“Valid String\n”); exit(0) ;}

 ;

s : A s B

 |

 ;

%%

int yyerror(char *msg)

{

 printf(“Invalid String\n”);

 exit(0);

}

main ()

{

 printf(“Enter the String\n”);

 yyparse();

}

Lex Part :

%{

 #include “y.tab.h”

%}

%%

[aA] { return A; }

[bB] { return B; }

\n { return NL ;}

. { return yytext[0]; }

%%