C++17 STL Cookbook

How to do it...

We are going to build our own transform_if function which works by supplying std::accumulate with the right function objects:

1. We need to include some headers, as always:

      #include <iostream>      #include <iterator>      #include <numeric>

2. First, we will implement a function called map. It accepts an input-transforming function as parameter and returns a function object, which works well together with std::accumulate:

      template <typename T>      auto map(T fn)      {

 

3. What we return is a function object that accepts a reduce function. When this object is called with such a reduce function, it returns another function object, which accepts an accumulator and an input parameter. It calls the reduce function on this accumulator and the ...