bool luhnCheck(long num)
{
    int a = 2;
    int b;
    int total = 0;
    int incrementer = 0;
    long shift = 1;
    while(a != 0)
    {
        incrementer++;
        for(int i = 1; i<=incrementer; i++)
        {
            shift *= 100;
        }
        a = num % shift;
        b = a/(shift/10); //- a % (shift/10); // every other digit
starting from the second to last one
        if(a!= 0)
        {
            total+= ((2*b) % 10) - ((2*b)/10); //sum of digits
        }

    }

return total;