C++ Program to Check Prime Number Using User-defined Function.

/* C++ program to check Prime number. */

#include <iostream>

using namespace std;

int check_prime(int n);

int main()

{

  int n, temp=0;

  cout << "Enter a positive  integer: ";

  cin >> n;

  temp=check_prime(n);

 

  if(temp==0)

    cout << n << " is a prime number.";

  else

    cout << n << " is not a prime number.";

  return 0;

}

int check_prime(int n)

{

  int i, flag=0;

  for(i=2;i<=n/2;++i)

  {

      if(n%i==0)

      {

          flag=1;

          break;

      }

  }

  return flag;

}

Output

Enter a positive integer: 371

371 is an Armstrong number.