/* IsPrime Testing Area This code is a little testing area to mess around with algorithms which test if a number is a prime number. In this case I benchmark the three variations for a range from 0 - 100 000. */ #include #include bool isPrime(int n) { if (n <= 3) { return n > 1; } else if (n % 2 == 0 || n % 3 == 0) { return false; } for (int i = 5; i * i <= n; i += 6) { if (n % i == 0 || n % (i + 2) == 0) { return false; } } return true; } bool isPrime2(int n) { if (n <= 3) { return n > 1; } for (int i = 2; i < n; i++) { if ((n % i) == 0) return false; } return true; } bool isPrime3(int n) { if (n <= 3) return n > 1; if (n % 2 == 0 || n % 3 == 0) return false; for (int i = 5; i <= n / 4; i += 2) { if ((n % i) == 0) return false; } return true; } int main() { int PrimeStart = 0; int PrimeMax = 100000; int counter1 = 0; int counter2 = 0; int counter3 = 0; //IsPrime optimized auto start = std::chrono::high_resolution_clock::now(); for (int i = PrimeStart; i <= PrimeMax; i++) { if (isPrime(i)) { //std::cout << i << std::endl; counter1++; } } auto finish = std::chrono::high_resolution_clock::now(); std::chrono::duration elapsed = finish - start; std::cout << "Elapsed time : " << elapsed.count() << " s\n"; std::cout << "Primenumber count: " << counter1 << std::endl; //IsPrime not optimized auto start2 = std::chrono::high_resolution_clock::now(); for (int i = PrimeStart; i <= PrimeMax; i++) { if (isPrime2(i)) { //std::cout << i << std::endl; counter2++; } } auto finish2 = std::chrono::high_resolution_clock::now(); std::chrono::duration elapsed2 = finish2 - start2; std::cout << "Elapsed time 2: " << elapsed2.count() << " s\n"; std::cout << "Primenumber count: " << counter2 << std::endl; //IsPrime Test auto start3 = std::chrono::high_resolution_clock::now(); for (int i = PrimeStart; i <= PrimeMax; i++) { if (isPrime3(i)) { //std::cout << i << std::endl; counter3++; } } auto finish3 = std::chrono::high_resolution_clock::now(); std::chrono::duration elapsed3 = finish3 - start3; std::cout << "Elapsed time 3: " << elapsed3.count() << " s\n"; std::cout << "Primenumber count: " << counter3 << std::endl; return 0; }

IsPrime Benchmarks