C++ High Performance

std::transform_reduce

As an addition to the STL algorithms, std::transform_reduce has also been added. It does exactly what it says; it transforms a range of elements as std::transform and then applies a functor. This accumulates them out of order, like std::reduce:

auto mice = std::vector<std::string>{"Mickey","Minnie","Jerry"}; 
auto num_chars = std::transform_reduce( 
  mice.begin(),  
  mice.end(),  
  size_t{0}, 
  [](const std::string& m) { return m.size(); }, // Transform 
  [](size_t a, size_t b) { return a + b; }       // Reduce 
); 
// num_chars is 17