%{
#include <stdio.h>
%}

%%
"if"|"else"|"int"|"float"|"return" {printf("keyword : %s\n", yytext);}
[a-zA-Z][a-zA-Z0-9]* {printf("Identifier : %s\n", yytext); }
[-+][0-9]+ {printf("signed integer : %s\n" , yytext); }
[0-9]+ {printf("unsigned integer : %s\n " , yytext); }
[ \t\n] {/*skip*/}
. {printf("unknown : %s\n" , yytext); }
%%

int yywrap() {return 1 ; }

int main(){
   printf(" enter the string : " ) ;
   yylex() ;
  return 0 ;
  }