Is prime

isprime.cc

#include <iostream>
#include <cmath>

template<typename T, typename std::enable_if<std::is_integral<T>::value>::type* = nullptr>
bool is_prime(T n) {
  if (n < 2) {
    return false;
  }
  for (T i = 2, sq = sqrt(n) + 1; i != sq; i++) {
    if (n % i == 0) {
      return false;
    }
  }
  return true;
}

int main() {
  std::cout << is_prime(101) << std::endl;
  return 0;
}