Re: copy from keys from multimap into the vector
Obnoxious User wrote:
#include <vector>
#include <map>
#include <iterator>
#include <algorithm>
#include <iostream>
template<typename C, typename M>
class key_inserter :
public std::iterator<std::output_iterator_tag,void,void,void,void> {
private:
C & d_coll;
public:
key_inserter(C & c) : d_coll(c) {}
key_inserter & operator*() { return *this; }
key_inserter & operator++() { return *this; }
key_inserter & operator++(int) { return *this; }
key_inserter &
operator=(typename M::value_type const & p) {
d_coll.push_back(p.first);
return *this;
}
};
template<typename C, typename M>
key_inserter<C,M> make_key_inserter(C & c, M & m) {
return key_inserter<C,M>(c);
}
int main() {
std::vector<int> v;
std::map<int,int> m;
m[0];m[1];m[2];m[6];
std::copy(m.begin(),
m.end(),
make_key_inserter(v,m));
std::copy(v.begin(),
v.end(),
std::ostream_iterator<int>(std::cout,"\n"));
return 0;
}
Given that the while loop solution only requires 2 lines of code, I
think it's the easier solution... ;)
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September 13, 1939