C++ program to Check Whether a Number can be Express as Sum of Two Prime Numbers

#include <iostream>
using namespace std;
int check_prime(int n);
int main()
{
    int n, i, flag=0;
    cout << "Enter a positive  integer: ";
    cin >> n;
    for(i=2; i<=n/2; ++i)
    {
        if (check_prime(i)==0)
        {
            if ( check_prime(n-i)==0)
            {
                cout << n << " = " << i << " + " << n-i << endl;
                flag=1;
            }

        }
    }
    if (flag==0)
      cout << n << " can't be expressed as sum of two prime numbers.";
    return 0;
}
int check_prime(int n) /*check prime number*/
{
  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: 34
34 = 3 + 31
34 = 5 + 29
34 = 11 + 23
34 = 17 + 17