Use reverse iterator adapters to iterate backward

A reverse iterator adapter is an abstraction that reverses the direction of an iterator class. It requires a bidirectional iterator.

How to do it…

Most bidirectional containers in the STL include a reverse iterator adapter. Other containers, such as the primitive C-array, do not. Let's look at some examples:

• Let's start with the printc() function we've used throughout this chapter:

  void printc(const auto & c, const string_view s = "") {
      if(s.size()) cout << format("{}: ", s);
      for(auto e : c) cout << format("{} ", e);
      cout << '\n';
  }

This uses a range-based for loop to print the elements of a container.

• The range-based for loop works even with primitive C-arrays, which have no iterator class. So, our printc() function already works with a C-array:

  int main...