YACC PROGRAM to recognize valid arithmetic expression that use operators + - * /.

Program to recognize valid arithmetic expression that use operators + - * /.

4a.l file ->

%{

#include "y.tab.h"

%}

%%

[a-zA-Z] {return ID;}

[0-9]+ {return NUMBER;}

[ \t] {;}

\n {return 0;}

. { return yytext[0];}

%%       

 

4a.y file

%{

#include<stdio.h>

%}

%token ID NUMBER

%left '+' '-'

%left '*' '/'

%%

stmt:expr

    ;

expr: expr '+' expr

    | expr '-' expr

    | expr '*' expr

    | expr '/' expr

    | '(' expr ')'

    | NUMBER

    | ID

    ;

%%

void main()

{

printf("enter expr : \n");

yyparse();

printf("valid exp");

exit(0);

}

void yyerror()

{

  printf("invalid exp");

exit(0);

}