Ex-5-RECOGNITION-OF-THE-GRAMMAR-anb-where-n-10-USING-YACC

RECOGNITION OF THE GRAMMAR(anb where n>=10) USING YACC

NAME: Nandhakumar G R

REG NO:212222100029

Aim:

To write a YACC program to recognize the grammar anb where n>=10.

ALGORITHM

1. Start the program.
2. Write a program in the vi editor and save it with .l extension.
3. In the lex program, write the translation rules for the variables a and b.
4. Write a program in the vi editor and save it with .y extension.
5. Compile the lex program with lex compiler to produce output file as lex.yy.c. eg $ lex filename.l
6. Compile the yacc program with yacc compiler to produce output file as y.tab.c. eg $ yacc –d arith_id.y
7. Compile these with the C compiler as gcc lex.yy.c y.tab.c
8. Enter a string as input and it is identified as valid or invalid.

PROGRAM:\

PROGRAM 1:

%{
/* Definition section */
#include "y.tab.h"
%}

/* Rule Section */
%%
[aA] {return A;}
[bB] {return B;}
\n {return NL;}
. {return yytext[0];}
%%

int yywrap()
{
    return 1;
}

PROGRAM 2:

%{
/* Definition section */
#include<stdio.h>
#include<stdlib.h>
%}

%token A B NL

/* Rule Section */
%%
stmt: S NL { 
    printf("valid string\n");
    exit(0); 
}
;
S: A S B |
;
%%

int yyerror(char *msg)
{
    printf("invalid string\n"); 
    exit(0);
}

//driver code 
int main()
{
    printf("enter the string\n"); 
    yyparse();
    return 0;
}

OUTPUT

RESULT

The YACC program to recognize the grammar anb where n>=10 is executed successfully and the output is verified.