Simple binary multiplier

#include <iostream>

int bin_mult(int a, int b)
{
    int res = 0;
    while(b)
    {
        if (b & 1) res += a;
        a <<= 1;
        b >>= 1;
    }
    return res;
}

int main()
{
    std::cout << bin_mult(100, 100) << std::endl;
}