Question

Here’s my code to find the prime factors of a number :

#include <iostream>
using namespace std;

int main()
{
    long int a, b, c, d = 0, f;
    int w = 0;

    f = 13195;

    for(a = 3; a < 100; a++)
    {
        w = f % a;

        if(w == 0)
        {
            for(b = 2; b < a; b++)
            {
                d = 0;
                c = a % b;
                if(c == 0)
                {
                    d++;
                    break;
                }
            }

            if(d == 0)
                cout << a << " is a prime\n";
        }
    }

    system("pause");

    return 0;
}

f is the number to be checked. I have to check a 12 digit number, but I cannot use double and long int as % cannot act on both together. What can I do instead?

Answer 1

A long long is a larger data type that can handle 64-bit (>12 digit) numbers. Using that should work.