#include <algorithm>
#include <iostream>
#include <string>
 
void comb(int N, int K)
{
    std::string bitmask(K, 1); // K leading 1's
    bitmask.resize(N, 0); // N-K trailing 0's
 
    // print integers and permute bitmask
    do {
        for (int i = 0; i < N; ++i) // [0..N-1] integers
        {
            if (bitmask[i]) std::cout << " " << i;
        }
        std::cout << std::endl;
    } while (std::prev_permutation(bitmask.begin(), bitmask.end()));
}
 
int main()
{
    comb(5, 3);
}

For the record, we can also use standard library now for these permutations, avoiding extra code : http://rosettacode.org/wiki/Combinations#C.2B.2B In the Rosetta code example, we do the permutation on a bitfield that can be used as a mask on the object array later to get the permutations we want ```c++ #include <algorithm> #include <iostream> #include <string> void comb(int N, int K) { std::string bitmask(K, 1); // K leading 1's bitmask.resize(N, 0); // N-K trailing 0's // print integers and permute bitmask do { for (int i = 0; i < N; ++i) // [0..N-1] integers { if (bitmask[i]) std::cout << " " << i; } std::cout << std::endl; } while (std::prev_permutation(bitmask.begin(), bitmask.end())); } int main() { comb(5, 3); } ```