exprtk_prime_sieve.cpp

/*
 **************************************************************
 *         C++ Mathematical Expression Toolkit Library        *
 *                                                            *
 * ExprTk Sieve Of Eratosthenes                               *
 * Author: Arash Partow (1999-2023)                           *
 * URL: https://www.partow.net/programming/exprtk/index.html  *
 *                                                            *
 * Copyright notice:                                          *
 * Free use of the Mathematical Expression Toolkit Library is *
 * permitted under the guidelines and in accordance with the  *
 * most current version of the MIT License.                   *
 * https://www.opensource.org/licenses/MIT                    *
 *                                                            *
 **************************************************************
*/


#include <cstdio>
#include <iostream>
#include <string>

#include "exprtk.hpp"


template <typename T>
void sieve_of_eratosthenes()
{
   typedef exprtk::expression<T> expression_t;
   typedef exprtk::parser<T>     parser_t;

   const std::string sieve_of_eratosthenes_program =
                  " var sieve[10^8] := [false];                 "
                  " var m := trunc(sqrt(sieve[]));              "
                  "                                             "
                  " sieve[0] := true;                           "
                  " sieve[1] := true;                           "
                  "                                             "
                  " for (var i := 0; i <= m; i += 1)            "
                  " {                                           "
                  "   if (false == sieve[i])                    "
                  "   {                                         "
                  "     for (var j := i^2; j < sieve[]; j += i) "
                  "     {                                       "
                  "       sieve[j] := true;                     "
                  "     }                                       "
                  "   }                                         "
                  " };                                          "
                  "                                             "
                  " var prime_count := sieve[] - sum(sieve);    "
                  "                                             "
                  " prime_count == 5761455;                     ";

   expression_t expression;

   parser_t parser;
   parser.compile(sieve_of_eratosthenes_program,expression);

   exprtk::timer timer;
   timer.start();

   const T result = expression.value();

   timer.stop();

   printf("Result: %8.3f\n",result);

   printf("Total time: %8.3fsec\n",timer.time());
}

int main()
{
   sieve_of_eratosthenes<double>();
   return 0;
}