# include <cstdlib>
# include <ctime>
# include <iomanip>
# include <iostream>

using namespace std;

# include "prime_pi.hpp"

int main ( );
void prime_pi1_test ( );
void pi_values ( int &n_data, int &n, int &p );
void timestamp ( );

//****************************************************************************80

int main ( )

//****************************************************************************80
//
//  Purpose:
//
//    prime_pi_test() tests prime_pi().
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    31 December 2022
//
//  Author:
//
//    John Burkardt
//
{
  timestamp ( );
  cout << "\n";
  cout << "prime_pi_test():\n";
  cout << "  C++ version\n";
  cout << "  Test prime_pi()\n";

  prime_pi1_test ( );
/*
  Terminate.
*/
  cout << "\n";
  cout << "prime_pi_test():\n";
  cout << "  Normal end of execution.\n";
  cout << "\n";
  timestamp ( );

  return 0;
}
//****************************************************************************80

void prime_pi1_test ( )

//****************************************************************************80
/*
  Purpose:

    prime_pi1_test() tests prime_pi1().

  Licensing:

    This code is distributed under the MIT license.

  Modified:

    31 December 2022

  Author:

    John Burkardt
*/
{
  int n;
  int n_data;
  int pi1;
  int pi2;

  cout << "\n";
  cout << "prime_pi1_test():\n";
  cout << "  Test prime_pi1()\n";
  cout << "           n          Pi(n)          prime_pi1(n)\n";
  cout << "\n";

  n_data = 0;

  while ( true )
  {
    pi_values ( n_data, n, pi1 );

    if ( n_data == 0 )
    {
      break;
    }

    pi2 = prime_pi1 ( n );

    cout << setw(12) << n
         << setw(10) << pi1
         << setw(10) << pi2 << "\n";

  }

  return;
}
//****************************************************************************80

void pi_values ( int &n_data, int &n, int &p )

//****************************************************************************80
//
//  Purpose:
//
//    pi_values() returns values of the Pi function.
//
//  Discussion:
//
//    Pi[n] is the number of primes less than or equal to n.
//
//    In Mathematica, the function can be evaluated by:
//
//      PrimePi[n]
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    31 December 2022
//
//  Author:
//
//    John Burkardt
//
//  Reference:
//
//    Stephen Wolfram,
//    The Mathematica Book,
//    Fourth Edition,
//    Cambridge University Press, 1999,
//    ISBN: 0-521-64314-7,
//    LC: QA76.95.W65.
//
//  Input:
//
//    int &N_DATA.  The user sets N_DATA to 0 before the first call.  
//
//  Output:
//
//    int &N_DATA.  On each call, the routine increments N_DATA by 1, and
//    returns the corresponding data; when there is no more data, the
//    output value of N_DATA will be 0 again.
//
//    int &N, the argument.
//
//    int &P, the value of the function.
//
{
# define N_MAX 21

  static int n_vec[N_MAX] = {
            1, 
            2, 
            4, 
            8, 
           16, 
           32, 
           64, 
          128, 
          256, 
          512, 
         1024, 
         2048, 
         4096, 
         8192, 
        16384, 
        32768, 
        65536, 
       131072, 
       262144, 
       524288, 
      1048576 };

  static int p_vec[N_MAX] = {
             0, 
             1, 
             2, 
             4, 
             6, 
            11, 
            18, 
            31, 
            54, 
            97, 
           172, 
           309, 
           564, 
          1028, 
          1900, 
          3512, 
          6542, 
         12251, 
         23000, 
         43390, 
         82025 };

  if ( n_data < 0 )
  {
    n_data = 0;
  }

  n_data = n_data + 1;

  if ( N_MAX < n_data )
  {
    n_data = 0;
    n = 0;
    p = 0;
  }
  else
  {
    n = n_vec[n_data-1];
    p = p_vec[n_data-1];
  }

  return;
# undef N_MAX
}
//****************************************************************************80

void timestamp ( )

//****************************************************************************80
//
//  Purpose:
//
//    timestamp() prints the current YMDHMS date as a time stamp.
//
//  Example:
//
//    31 May 2001 09:45:54 AM
//
//  Licensing:
//
//    This code is distributed under the MIT license. 
//
//  Modified:
//
//    19 March 2018
//
//  Author:
//
//    John Burkardt
//
{
# define TIME_SIZE 40

  static char time_buffer[TIME_SIZE];
  const struct std::tm *tm_ptr;
  std::time_t now;

  now = std::time ( NULL );
  tm_ptr = std::localtime ( &now );

  std::strftime ( time_buffer, TIME_SIZE, "%d %B %Y %I:%M:%S %p", tm_ptr );

  std::cout << time_buffer << "\n";

  return;
# undef TIME_SIZE
}