C++17 STL Cookbook

How to do it...

In this section, we will implement a primitive iterator that counts numbers and use it together with an STL algorithm, which initially does not compile with it. Then we do what's necessary to make it STL-compatible.

1. First, we need to include some headers, as always:

      #include <iostream>      #include <algorithm>

 

2. Then we implement a primitive number counting iterator, as in the previous section. When iterating over it, it will emit plain increasing integers. The num_range acts as a handy begin and end iterator donor:

      class num_iterator       {          int i;      public:                explicit num_iterator(int position = 0) : i{position} {}                int operator*() const { return i; }                num_iterator& operator++() {              ++i;              return *this;          }       bool operator!=(const num_iterator ...