Program in YACC to recognize the language (a^n b , n>=10). (output to say input is valid or not)

/* program to check whether the given string is  a part of the language a^n b or not */

File Name : pr12.y

%{

 #include<stdio.h>

 int yylex(void);

 int yyerror(char *);

 %}

%token A B   //tokens : the alphabets of language 'a' and 'b' 

%%

//production rules for grammar

expr: s B         

  ;

s : s A 

| A   

;

%%

int main()

{

 

 printf("Enter the string \n");

 yyparse(); 

 return 0;

}

int yyerror(char *s)

{

 printf("Invalid: Not a part of the language - a^n b \n");

}

File Name : pr12.l

%{

 #include "y.tab.h"

 extern int yylval;

%}

A [a]

B [b]

%%

{A} {yylval=yytext[0];return A;}

{B} {yylval=yytext[1];return B;}

\n {return 0;}

. {return yytext[0];}

%%

Output: