need help with Goldbach's Conjecture!

[ineedabreakfosho]

I can't seem to get this code to work:
it needs to find the sum of two prime numbers, and I need to do it it without any scanf or printf implements. Thanks to anyone who can help me out! XD

Here's what I have so far:

#include<iostream>
using namespace std;

bool is_divisible(int, int);
bool is_prime(int);

void main()
{
	int n;
	int p1, p2;

	cout << "\n Enter a number: ";
	cin  >> n;

	for (p1=2, p2=2; p1 <= n; p1++)
	if ((is_prime(p1)) && (is_prime(n-p1)))
	cout << n << " = " << (is_prime(p1)) << " + " << (is_prime(p2));

	cout << "\n\n";

}

bool is_divisible (int x, int y)
{
	if(x%y == 0)
		return true;
	else 
		return false;
}

bool is_prime(int a)
{
	for (int i = a/2; i >1; i--)
		if (is_divisible(a, i))
			return false;
	return true;
}

[z05DSL3A]

I have made a few minor changes to the for loop

    for (p1=2; p1 <= n; p1++)
    {
        if ((is_prime(p1)) && (is_prime(n-p1)))
        {
            cout << n << " = " << p1 << " + " << n-p1 << endl;
        }
    }