SS 6.B - YACC - RECOGNIZE VALID IDENTIFIER, OPERATORS AND KEYWORDS

6 - b) Write YACC program to recognize valid identifier, operators and keywords in the given text (C program) file.

lab6.l PROGRAM

%{
#include <stdio.h>
#include "y.tab.h"
extern yylval;
%}

%%
[ \t];
[+|-|*|/|=|<|>] {printf("operator is %s\n",yytext);return OP;}
[0-9]+ {yylval = atoi(yytext); printf("numbers is %d\n",yylval); return DIGIT;}
int|char|bool|float|void|for|do|while|if|else|return|void {printf("keyword is %s\n",yytext);return KEY;}
[a-zA-Z0-9]+ {printf("identifier is %s\n",yytext);return ID;}
. ;
%%

lab6.y PROGRAM

%{
#include <stdio.h>
#include <stdlib.h>
int id=0, dig=0, key=0, op=0;
%}
%token DIGIT ID KEY OP

%%
input:
DIGIT input { dig++; }
| ID input { id++; }
| KEY input { key++; }
| OP input {op++;}
| DIGIT { dig++; }
| ID { id++; }
| KEY { key++; }
| OP { op++;}
;
%%

#include <stdio.h>
extern int yylex();
extern int yyparse();
extern FILE *yyin;
main()
{
FILE *myfile = fopen("inputfile.c", "r");
if (!myfile)
{
printf("I can't open inputfile.c!");
return -1;
}
yyin = myfile;
do{
yyparse();
}while (!feof(yyin));
printf("numbers = %d\nKeywords = %d\nIdentifiers = %d\noperators = %d\n",dig, key,id, op);
}

void yyerror()
{
printf("EEK, parse error! Message: ");
exit(-1);
}

inputfile.txt FILE

#include<stdio.h>

int main()
{
int a ;
int b ;
a = 1 ;
b = 2 ;
a = a+b;
return 0 ;
}


OUTPUT :( click on image to zoom )