Print all prime numbers between two unknown numbers n and x?

Answer 1

#include<iostream>

#include<cmath>

#include<utility>

bool is_prime (const unsigned n) {

if (n<2) return false;

if (!(n%2)) return n==2;

unsigned max_factor=(unsigned)sqrt((double)n)+1;

for (unsigned factor=3; factor<max_factor; ++factor) {

if (!(n%factor)) return false;

}

return true;

}

void print_primes(const unsigned low, const unsigned high) {

for (int i=low; i<=high; ++i) {

if (is_prime (i)) std::cout<<i<<std::endl;

}

}

int main () {

unsigned n, x;

std::cout<<"Print prime numbers\nFrom: ";

std::cin>>n;

std::cout<<"To: ";

std::cin>>x;

if (x<n) std::swap(x,n);

print_primes (n, x);

}