Re: copy from keys from multimap into the vector
On Oct 29, 2:33 pm, puzzlecracker <ironsel2...@gmail.com> wrote:
I am using while loop for that but I am sure you can do it quicker and
more syntactically clear with copy function.
Here is what I do and would like to if someone has a cleaner solution:
vector<string> vec;
multimap<stirng, int> myMap
// populate myMap
multimap<string, int >::iterator iter = myMap.begin();
while(iter != myMap.end())
{
vec.push_back(iter->first)
}
You'll need a functor to extract that string from multimap's
value_type and std::transform can process the elements.
#include <iostream>
#include <ostream>
#include <string>
#include <vector>
#include <map>
#include <iterator>
template< typename P >
struct extract_first
{
const typename P::first_type&
operator()(const P& p) const
{
return p.first;
}
};
int main()
{
std::vector< std::string > vec;
std::multimap< std::string, int > mm;
// populate mm
typedef std::multimap< std::string, int >::value_type VType;
std::transform( mm.begin(),
mm.end(),
std::back_inserter(vec),
extract_first< VType >() );
}