prime numbers algorithm c++ code example

Example 1: c++ find prime numbers

#include <iostream>
using namespace std;

int main()
{
  int n, i;
  bool isPrime = true;

  cout << "Enter a positive integer: ";
  cin >> n;

  for(i = 2; i <= n / 2; ++i)
  {
      if(n % i == 0)
      {
          isPrime = false;
          break;
      }
  }
  if (isPrime)
      cout << "This is a prime number";
  else
      cout << "This is not a prime number";

  return 0;
}

Example 2: prime number c++

template<class T> bool isPrime(T n) 
{ 
	T i;
  	if(i<2) return false;
	for(i = 2; i * i <= n; i++) { 
    	if(n % i == 0)  return false; 
    } 
	return true; 
}