Modern C++ Programming Cookbook

How it works...

These non-member functions were introduced in different versions of the standard, but all of them were modified in C++17 to return constexpr auto:

• std::begin() and std::end() in C++11
• std::cbegin()/std::cend(), std::rbegin()/std::rend(), and std::crbegin()/std::crend() in C++14
• std::data(), std::size(), and std::empty() in C++17

The begin()/end() family of functions have overloads for container classes and arrays, and all they do is the following:

• Return the results of calling the container-corresponding member function for containers.
• Return a pointer to the first or one-past-last element of the array for arrays.

The actual typical implementation for std::begin()/std::end() is the following:

    template<class C> constexpr ...