C++: Getting all k-length combinations of n numbers

C++: List All Combinations

#include <iostream>
#include <vector>

using namespace std;

class Combinations {
    int n;
    int k;
    vector<int> current;
    bool init;
public:
    Combinations(int n, int k): n(n), k(k), init(false) {
        current.resize(k);
    }

    bool next() {
        if (!init) {
            int val = 0;
            for (vector<int>::iterator it = current.begin();
                    it != current.end(); ++it) {
                *it = val++;
            }
            init = true;
        } else {
            vector<int>::iterator it = current.end() - 1;
            while (true) {
                if (*it < (n - 1)) {
                    bool yield = true;
                    int m = ++*it;
                    while (++it != current.end()) {
                        if (m < (n - 1)) {
                            *it = ++m;
                        } else {
                            --it;
                            yield = false;
                            break;
                        }
                    }
                    if (yield) {
                        break;
                    }
                } else {
                    if (current.begin() == it) {
                        return false;
                    } else {
                        --it;
                    }
                }
            }
        }
        return true;
    }
    
    const vector<int> &access() const {
        return current;
    }
    
    void dump() const {
        for (vector<int>::const_iterator it = current.begin();
                    it != current.end(); ++it) {
            cout << *it << " ";
        }
        cout << endl;
    }
};

int main() {
    Combinations cmb(5, 2);
    
    while(cmb.next()) {
        cmb.dump();
    }
    
    return 0;
}