YACC program which accept strings that starts and ends with 0 or 1

Problem: Write a YACC program which accept strings that starts and ends with Zero or One

Explanation:
YACC (Yet another Compiler-Compiler) is the standard parser generator for the Unix operating system. An open source program, yacc generates code for the parser in the C programming language. The acronym is usually rendered in lowercase but is occasionally seen as YACC or Yacc.

Examples:

Input: 001100
Output: Sequence Accepted

Input: 1001001
Output: Sequence Accepted

Input: 0011101
Output: Sequence Rejected

Input: 100110
Output: Sequence Rejected

Lexical Analyzer Source Code :

%{ 
  /* Definition section */
  extern int yylval; 
%} 
  
/* Rule Section */
%% 
  
0 {yylval = 0; return ZERO;} 
  
1 {yylval = 1; return ONE;} 
  
.|\n {yylval = 2; return 0;} 
  
%% 

Parser Source Code :

%{ 
  /* Definition section */
  #include<stdio.h> 
  #include <stdlib.h> 
  void yyerror(const char *str)  
  { 
   printf("\nSequence Rejected\n");         
  } 
  
%} 
  
%token ZERO ONE 
  
/* Rule Section */
%% 
  
r : s {printf("\nSequence Accepted\n\n");} 
; 
  
s : n 
| ZERO a 
| ONE b 
; 
  
a : n a 
| ZERO 
; 
  
b : n b 
| ONE 
; 
  
n : ZERO 
| ONE 
; 
  
%% 
  
#include"lex.yy.c" 
//driver code 
int main()  
 { 
    printf("\nEnter Sequence of Zeros and Ones : "); 
    yyparse(); 
    printf("\n"); 
    return 0; 
 } 

Output:

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