<br />//(Yacc File : Save as .y)
//to compile and Run
//:-> yacc -d FileName.y
//:-> lex FileName.l
//:-> gcc lex.yy.c y.tab.c -ll
//:-> ./a.output
//:-> enter input as - 101
//:-> output:-> 5
%{
#include<stdio.h>
#include<stdlib.h>
void yyerror(char *s);
%}
%token ZERO ONE
%%
N: L {printf("\n%d",$$);}
L: L B {$$=$1*2+$2;}
| B {$$=$1;}
B:ZERO {$$=$1;}
|ONE {$$=$1;};
%%
int main()
{
while(yyparse());
}
yyerror(char *s)
{
fprintf(stdout,"\n%s",s);
}
// (Lex File : save as .l)
%{
#include<stdio.h>
#include<stdlib.h>
#include"y.tab.h"
extern int yylval;
%}
%%
0 {yylval=0;return ZERO;}
1 {yylval=1;return ONE;}
[ \t] {;}
\n return 0;
. return yytext[0];
%%
Output :-
101
5
Myprogworld 