(C++) SumFirst

SumFirst is the answer of question #21 of Exercise #9: No for-loops.

You may contact me if you have an STL solution...

Boost.Bind SumFirst

Thanks to 'ofwolfandman':

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#include <functional> #include <numeric> #include <utility> #include <vector> #include <boost/bind.hpp> int SumFirst(const std::vector<std::pair<int,int> >& v) {   return std::accumulate(     v.begin(),     v.end(),     static_cast<int>(0),     boost::bind(       std::plus<int>(),       _1,       boost::bind<int>(&std::pair<int,int>::first, _2)       )     ); }

Boost.Lambda SumFirst

Thanks to 'ofwolfandman':

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#include <functional> #include <numeric> #include <utility> #include <vector> #include <boost/lambda/lambda.hpp> #include <boost/lambda/bind.hpp> int SumFirst(const std::vector<std::pair<int,int> >& v) {   return std::accumulate(     v.begin(),     v.end(),     static_cast<int>(0),     boost::lambda::_1     + boost::lambda::bind(       &std::pair<int, int>::first, boost::lambda::_2       )   ); }