c++ primality test
#include <iostream>
#include <cmath>
bool isPrime(int n) {
if (n <= 1) {
return false;
}
int sqrtN = std::sqrt(n);
for (int i = 2; i <= sqrtN; ++i) {
if (n % i == 0) {
return false;
}
}
return true;
}
int main() {
int num;
std::cout << "Enter a number: ";
std::cin >> num;
if (isPrime(num)) {
std::cout << num << " is a prime number." << std::endl;
} else {
std::cout << num << " is not a prime number." << std::endl;
}
return 0;
}