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///
/// @file count_primes1.cpp
/// @brief Count the primes up to 10^9.
///
/// Copyright (C) 2025 Kim Walisch, <kim.walisch@gmail.com>
///
/// This file is distributed under the BSD License. See the COPYING
/// file in the top level directory.
///
#include <ParallelSieve.hpp>
#include <primesieve/Vector.hpp>
#include <stdint.h>
#include <cstdlib>
#include <iostream>
#include <iomanip>
using namespace primesieve;
/// Correct pi(x) values to compare with test results
const Array<uint64_t, 9> pix =
{
4, // pi(10^1)
25, // pi(10^2)
168, // pi(10^3)
1229, // pi(10^4)
9592, // pi(10^5)
78498, // pi(10^6)
664579, // pi(10^7)
5761455, // pi(10^8)
50847534 // pi(10^9)
};
void check(bool OK)
{
std::cout << " " << (OK ? "OK" : "ERROR") << "\n";
if (!OK)
std::exit(1);
}
int main()
{
std::cout << std::left;
ParallelSieve ps;
uint64_t count = 0;
uint64_t stop = 1;
// pi(x) with x = 10^(i+1)
for (size_t i = 0; i < pix.size(); i++)
{
uint64_t start = stop + 1;
stop *= 10;
count += ps.countPrimes(start, stop);
std::cout << "pi(10^" << i + 1 << ") = " << std::setw(12) << count;
check(count == pix[i]);
}
// Test PreSieve with preSievePrimes <= 163.
// The thread interval must be sufficiently large
// otherwise minimal pre-sieving is used.
// Using a single thread increases thread interval.
ps.setNumThreads(1);
count = ps.countPrimes(0, (uint64_t) 1e9);
std::cout << "pi(10^9) = " << std::setw(12) << count;
check(count == 50847534);
std::cout << std::endl;
std::cout << "All tests passed successfully!" << std::endl;
return 0;
}
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